Re: RE: [PATCH] extcon : callback function to read cable property

Re: RE: [PATCH] extcon : callback function to read cable property

[MyungJoo Ham]

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> Myunjoo/Chanwoo
> 
> Ping...
> Could you please review this patch?
> 
> -jtc
> 
> > > > Subject: Re: [PATCH] extcon : callback function to read cable
> > > > property
> > > >
> > > > I think the reason why we have extcon is in first place is to only
> > > > notify the clients of cable connection and disconnection and it is
> > > > up to the client to decide what else to do with the cable such as
> > > > finding which state it is in and other details.
> > > > So I feel this should not be handled in the extcon.
> > > >
> > > > However it is up to the maintainer to decide.
> > >
> > > Once the consumer gets the notification, it needs to take some action.
> > > One of the action is to read the cable properties. This can be done by
> > > proprietary calls which is known both to the consumer and the provider.
> > > My intention is to avoid this proprietary calls. Since both the
> > > provider and consumer are communicating with the extcon subsystem , I
> > > feel having a callback function of this kind would help to avoid the
> > > use of proprietary calls. Also I agree that extcon notifier chains are
> > > used to notify the cable state (attach/detach). But if a cable has
> > > more than two states (like the charger cable) how do we support it without
> > having a callback function like this?
> > > Let the maintainer take the final decision.
> > Well this use case will keep on growing if we start factor in this kind of
> > changes and that is why I am opposed to adding any other state.
> > Maintainer?
> > >
> > >
> > 

Hello,


I don't think it's appropriate to declare the charger specific
properties in extcon.h. The status of a charger should be and can be
represented by an instance of regulator, power-supply-class,
or charger-manager.

Thus, we may (I'm still not sure) need to let extcon to relay
the instance (struct device? or char *devname?) with some callback
similar with get_cable_device().  However, allowing (and encouraging)
to pass void pointer of cable_props to extcon users from extcon device
appears not adequete. If the both parties can use their own "private"
data structure, why they cannot simply pass their own data witht the
"private" data channel?
 

Recap:
- The later part of patch: NACK
- The first part of patch (callback): need to reconsider the data type.
We may get device pointer or device name that is correspondant to the
cable, which in turn, guides us to the corresponding data structure
(charger-manager, regulator, or something) However, I'm still not sure
which should be appropriate for this.


Cheers!
MyungJoo
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RE: RE: [PATCH] extcon : callback function to read cable property

[Tc, Jenny]

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> > > > > Subject: Re: [PATCH] extcon : callback function to read cable
> > > > > property
> > > > >
> > > > > I think the reason why we have extcon is in first place is to
> > > > > only notify the clients of cable connection and disconnection
> > > > > and it is up to the client to decide what else to do with the
> > > > > cable such as finding which state it is in and other details.
> > > > > So I feel this should not be handled in the extcon.
> > > > >
> > > > > However it is up to the maintainer to decide.
> > > >
> > > > Once the consumer gets the notification, it needs to take some action.
> > > > One of the action is to read the cable properties. This can be
> > > > done by proprietary calls which is known both to the consumer and the
> provider.
> > > > My intention is to avoid this proprietary calls. Since both the
> > > > provider and consumer are communicating with the extcon subsystem
> > > > , I feel having a callback function of this kind would help to
> > > > avoid the use of proprietary calls. Also I agree that extcon
> > > > notifier chains are used to notify the cable state
> > > > (attach/detach). But if a cable has more than two states (like the
> > > > charger cable) how do we support it without
> > > having a callback function like this?
> > > > Let the maintainer take the final decision.
> > > Well this use case will keep on growing if we start factor in this
> > > kind of changes and that is why I am opposed to adding any other state.
> > > Maintainer?
> > > >
> > > >
> > >
> 
> Hello,
> 
> 
> I don't think it's appropriate to declare the charger specific properties in
> extcon.h. The status of a charger should be and can be represented by an
> instance of regulator, power-supply-class, or charger-manager.
> 
Agreed. We can move this to power supply subsystem.

> Thus, we may (I'm still not sure) need to let extcon to relay the instance
> (struct device? or char *devname?) with some callback similar with
> get_cable_device().  However, allowing (and encouraging) to pass void
> pointer of cable_props to extcon users from extcon device appears not
> adequete. If the both parties can use their own "private"
> data structure, why they cannot simply pass their own data witht the
> "private" data channel?
> 
> 
> Recap:
> - The later part of patch: NACK
> - The first part of patch (callback): need to reconsider the data type.
> We may get device pointer or device name that is correspondant to the
> cable, which in turn, guides us to the corresponding data structure (charger-
> manager, regulator, or something) However, I'm still not sure which should
> be appropriate for this.
> 

The requirement for this feature came from the implementation of the
power supply charging framework (http://www.spinics.net/lists/kernel/msg1420500.html 
refer charger_cable_event_worker function). The charging framework is not a driver. It can
be compiled with the power supply class driver to support charging. Also the
private data structure may not provide a generic method for this implementation
since the extcon provider drivers will be different in different platforms. So it's not
necessary that the framework knows the private data structure of the provider.
Basically the requirement is to have a generic method to retrieve the cable properties without
knowing the extcon provider driver internal implementation. Can you suggest a generic approach
for this problem?

Also the cable states we support in extcon (attach/detach) is not sufficient
to support the cable states of a charger cable which can have more than 2 states. The charger cable 
states can be (1)attach/(2)detach, (3)suspend - host suspend (different from detach since it's possible to charge
in this state but with a different charge current than the attached state),(4)resume - resume after the suspend,
(5)update - update the cable properties after USB enumeration (USB cable supports 100(USB2.0)/150(USB3.0)
in an un configured state. But after enumeration it can support up to 500mA(USB 2.0)/900(USB 3.0))

Since extcon is basically intended to support the cable states, how do we support cables with
more than two states?
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Re: [PATCH] extcon : callback function to read cable property

[Chanwoo Choi]

On 10/19/2012 12:13 PM, Tc, Jenny wrote:
> 
> 
>>>>>> Subject: Re: [PATCH] extcon : callback function to read cable
>>>>>> property
>>>>>>
>>>>>> I think the reason why we have extcon is in first place is to
>>>>>> only notify the clients of cable connection and disconnection
>>>>>> and it is up to the client to decide what else to do with the
>>>>>> cable such as finding which state it is in and other details.
>>>>>> So I feel this should not be handled in the extcon.
>>>>>>
>>>>>> However it is up to the maintainer to decide.
>>>>>
>>>>> Once the consumer gets the notification, it needs to take some action.
>>>>> One of the action is to read the cable properties. This can be
>>>>> done by proprietary calls which is known both to the consumer and the
>> provider.
>>>>> My intention is to avoid this proprietary calls. Since both the
>>>>> provider and consumer are communicating with the extcon subsystem
>>>>> , I feel having a callback function of this kind would help to
>>>>> avoid the use of proprietary calls. Also I agree that extcon
>>>>> notifier chains are used to notify the cable state
>>>>> (attach/detach). But if a cable has more than two states (like the
>>>>> charger cable) how do we support it without
>>>> having a callback function like this?
>>>>> Let the maintainer take the final decision.
>>>> Well this use case will keep on growing if we start factor in this
>>>> kind of changes and that is why I am opposed to adding any other state.
>>>> Maintainer?
>>>>>
>>>>>
>>>>
>>
>> Hello,
>>
>>
>> I don't think it's appropriate to declare the charger specific properties in
>> extcon.h. The status of a charger should be and can be represented by an
>> instance of regulator, power-supply-class, or charger-manager.
>>
> Agreed. We can move this to power supply subsystem.
> 
>> Thus, we may (I'm still not sure) need to let extcon to relay the instance
>> (struct device? or char *devname?) with some callback similar with
>> get_cable_device().  However, allowing (and encouraging) to pass void
>> pointer of cable_props to extcon users from extcon device appears not
>> adequete. If the both parties can use their own "private"
>> data structure, why they cannot simply pass their own data witht the
>> "private" data channel?
>>
>>
>> Recap:
>> - The later part of patch: NACK
>> - The first part of patch (callback): need to reconsider the data type.
>> We may get device pointer or device name that is correspondant to the
>> cable, which in turn, guides us to the corresponding data structure (charger-
>> manager, regulator, or something) However, I'm still not sure which should
>> be appropriate for this.
>>
> 
> The requirement for this feature came from the implementation of the
> power supply charging framework (http://www.spinics.net/lists/kernel/msg1420500.html 
> refer charger_cable_event_worker function). The charging framework is not a driver. It can
> be compiled with the power supply class driver to support charging. Also the
> private data structure may not provide a generic method for this implementation
> since the extcon provider drivers will be different in different platforms. So it's not
> necessary that the framework knows the private data structure of the provider.
> Basically the requirement is to have a generic method to retrieve the cable properties without
> knowing the extcon provider driver internal implementation. Can you suggest a generic approach
> for this problem?
> 
The rold of extcon inform only attached/detached state of extcon consumer driver
from extcon provider driver. After extcon consumer driver detect the state of cable
through extcon, extcon consumer driver or framework should get the additional information of cable
from other device driver except of extcon.

Also, extcon manage various cables (e.g., USB, TA, MHL, JIG-USB-ON, JIG-USB-OFF, Dock)
What are common properties among many cables expect attached or detached state?

> Also the cable states we support in extcon (attach/detach) is not sufficient
> to support the cable states of a charger cable which can have more than 2 states. The charger cable 
> states can be (1)attach/(2)detach, (3)suspend - host suspend (different from detach since it's possible to charge
> in this state but with a different charge current than the attached state),(4)resume - resume after the suspend,
> (5)update - update the cable properties after USB enumeration (USB cable supports 100(USB2.0)/150(USB3.0)
> in an un configured state. But after enumeration it can support up to 500mA(USB 2.0)/900(USB 3.0))
> 
> Since extcon is basically intended to support the cable states, how do we support cables with
> more than two states?

You explained about charger cable for charging framework. I think that extcon consumer driver
can detect the chagne of system state from idle to suspend, then extcon consumer driver change
charge current according to system state(idle or suspend).  Also, I think that the main of charging
is regulator and the regulator for charging defines max or min limitation of charge current with
H/W dependency. The extcon provider driver haven't decided the charge current according to cable type.

Now that extcon-max77693 MUIC device driver can detect difference between "MHL" and "MHL-TA"
when MHL/MHL-TA cable is attached/detached and define two type cable of MHL cable.

Thanks,
Chanwoo Choi

RE: [PATCH] extcon : callback function to read cable property

[Tc, Jenny]

> Subject: Re: [PATCH] extcon : callback function to read cable property
> 
> On 10/19/2012 12:13 PM, Tc, Jenny wrote:
> >
> >
> >>>>>> Subject: Re: [PATCH] extcon : callback function to read cable
> >>>>>> property
> >>>>>>
> >>>>>> I think the reason why we have extcon is in first place is to
> >>>>>> only notify the clients of cable connection and disconnection and
> >>>>>> it is up to the client to decide what else to do with the cable
> >>>>>> such as finding which state it is in and other details.
> >>>>>> So I feel this should not be handled in the extcon.
> >>>>>>
> >>>>>> However it is up to the maintainer to decide.
> >>>>>
> >>>>> Once the consumer gets the notification, it needs to take some
> action.
> >>>>> One of the action is to read the cable properties. This can be
> >>>>> done by proprietary calls which is known both to the consumer and
> >>>>> the
> >> provider.
> >>>>> My intention is to avoid this proprietary calls. Since both the
> >>>>> provider and consumer are communicating with the extcon
> subsystem
> >>>>> , I feel having a callback function of this kind would help to
> >>>>> avoid the use of proprietary calls. Also I agree that extcon
> >>>>> notifier chains are used to notify the cable state
> >>>>> (attach/detach). But if a cable has more than two states (like the
> >>>>> charger cable) how do we support it without
> >>>> having a callback function like this?
> >>>>> Let the maintainer take the final decision.
> >>>> Well this use case will keep on growing if we start factor in this
> >>>> kind of changes and that is why I am opposed to adding any other
> state.
> >>>> Maintainer?
> >>>>>
> >>>>>
> >>>>
> >>
> >> Hello,
> >>
> >>
> >> I don't think it's appropriate to declare the charger specific
> >> properties in extcon.h. The status of a charger should be and can be
> >> represented by an instance of regulator, power-supply-class, or charger-
> manager.
> >>
> > Agreed. We can move this to power supply subsystem.
> >
> >> Thus, we may (I'm still not sure) need to let extcon to relay the
> >> instance (struct device? or char *devname?) with some callback
> >> similar with get_cable_device().  However, allowing (and encouraging)
> >> to pass void pointer of cable_props to extcon users from extcon
> >> device appears not adequete. If the both parties can use their own
> "private"
> >> data structure, why they cannot simply pass their own data witht the
> >> "private" data channel?
> >>
> >>
> >> Recap:
> >> - The later part of patch: NACK
> >> - The first part of patch (callback): need to reconsider the data type.
> >> We may get device pointer or device name that is correspondant to the
> >> cable, which in turn, guides us to the corresponding data structure
> >> (charger- manager, regulator, or something) However, I'm still not
> >> sure which should be appropriate for this.
> >>
> >
> > The requirement for this feature came from the implementation of the
> > power supply charging framework
> > (http://www.spinics.net/lists/kernel/msg1420500.html
> > refer charger_cable_event_worker function). The charging framework is
> > not a driver. It can be compiled with the power supply class driver to
> > support charging. Also the private data structure may not provide a
> > generic method for this implementation since the extcon provider
> > drivers will be different in different platforms. So it's not necessary that the
> framework knows the private data structure of the provider.
> > Basically the requirement is to have a generic method to retrieve the
> > cable properties without knowing the extcon provider driver internal
> > implementation. Can you suggest a generic approach for this problem?
> >
> The rold of extcon inform only attached/detached state of extcon consumer
> driver from extcon provider driver. After extcon consumer driver detect the
> state of cable through extcon, extcon consumer driver or framework should
> get the additional information of cable from other device driver except of
> extcon.
> 
> Also, extcon manage various cables (e.g., USB, TA, MHL, JIG-USB-ON, JIG-
> USB-OFF, Dock) What are common properties among many cables expect
> attached or detached state?
> 

For charger cable the current each cable can provide will be common.
But may not be relevant for other cables. 

I understand your point on extcon role. But my concern is, when the consumer
driver gets a notification on cable state change, how does the consumer query the
cable properties in a generic way. Do you have any suggestions for this?

A use case can be as below

When a USB host cable (SDP) connected to the platform, without USB enumeration
it can support only up to 100mA(USB2.)/150mA(USB 3.0) (As per USB charging spec).
Once the enumeration is done this can be 500mA/950mA. If the consumer charger driver
need to configure the charger chip, it need to know the charger cable capabilities.
For example a platform PLAT1 may have charger driver CHRGR1 and OTG driver OTG1.
But platform PLAT2 may have CHGR1 but different OTG driver OTG2. How 
CHGR1 driver can detect  the cable properties without having any platform layer
hooks? The platform layer hooks (using platform data)will work only if the consumer is
a platform driver. What if it's a framework which will have the same flow in all platforms?

> > Also the cable states we support in extcon (attach/detach) is not
> > sufficient to support the cable states of a charger cable which can
> > have more than 2 states. The charger cable states can be
> > (1)attach/(2)detach, (3)suspend - host suspend (different from detach
> > since it's possible to charge in this state but with a different
> > charge current than the attached state),(4)resume - resume after the
> > suspend, (5)update - update the cable properties after USB enumeration
> > (USB cable supports 100(USB2.0)/150(USB3.0) in an un configured state.
> > But after enumeration it can support up to 500mA(USB 2.0)/900(USB
> > 3.0))
> >
> > Since extcon is basically intended to support the cable states, how do
> > we support cables with more than two states?
> 
> You explained about charger cable for charging framework. I think that
> extcon consumer driver can detect the chagne of system state from idle to
> suspend, then extcon consumer driver change charge current according to
> system state(idle or suspend).  Also, I think that the main of charging is
> regulator and the regulator for charging defines max or min limitation of
> charge current with H/W dependency. The extcon provider driver haven't
> decided the charge current according to cable type.
> 

I was referring to the host suspend case when we use SDP cable. For example if the
cable is connected to a host machine to charger a target, the charger current supplied by
the host will vary based on the HOST power state. For example if it's in suspend, some platforms
support 500mA but other platforms may prefer to comply USB spec ie 2.5mA.

> Now that extcon-max77693 MUIC device driver can detect difference
> between "MHL" and "MHL-TA"
> when MHL/MHL-TA cable is attached/detached and define two type cable of
> MHL cable.
> 
> Thanks,
> Chanwoo Choi

[PATCH] extcon : callback function to read cable property

[Jenny TC]

For some cables a boolean variable will not be enough to represent
the state and properties of the cable. For example a charger cable can
have states CONNECT,DISCOONECT,SUSPEND(Host suspend for SDP cable),
RESUME(Host wakeup), and UPDATE (to increase the charge
current after USB enumaeration).Also the properties of the cable may
vary based on the state. FOr example in SUSPENDED state platforms can
support 0/100/500/950(USB 3.0) mA based on the HW. To initiate charging
the consumer should be able to get the charger properties dynamically.

Signed-off-by: Jenny TC <jenny.tc@intel.com>
---
 include/linux/extcon.h |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/include/linux/extcon.h b/include/linux/extcon.h
index 073fd49..2e61ee0 100644
--- a/include/linux/extcon.h
+++ b/include/linux/extcon.h
@@ -122,6 +122,7 @@ struct extcon_dev {
 	/* --- Optional callbacks to override class functions --- */
 	ssize_t	(*print_name)(struct extcon_dev *edev, char *buf);
 	ssize_t	(*print_state)(struct extcon_dev *edev, char *buf);
+	int (*get_cable_properties)(const char *cable_name, void *cable_props);
 
 	/* --- Internal data. Please do not set. --- */
 	struct device	*dev;
@@ -177,6 +178,19 @@ struct extcon_specific_cable_nb {
 	unsigned long previous_value;
 };
 
+enum extcon_chrgr_cbl_stat {
+	EXTCON_CHRGR_CABLE_CONNECTED,
+	EXTCON_CHRGR_CABLE_DISCONNECTED,
+	EXTCON_CHRGR_CABLE_SUSPENDED,
+	EXTCON_CHRGR_CABLE_RESUMED,
+	EXTCON_CHRGR_CABLE_UPDATED,
+};
+
+struct extcon_chrgr_cbl_props {
+	enum extcon_chrgr_cbl_stat cable_stat;
+	unsigned long mA;
+};
+
 #if IS_ENABLED(CONFIG_EXTCON)
 
 /*
-- 
1.7.9.5

Re: [PATCH] extcon : callback function to read cable property

[anish kumar]

On Wed, 2012-10-10 at 15:53 +0530, Jenny TC wrote:
> For some cables a boolean variable will not be enough to represent
> the state and properties of the cable. For example a charger cable can
> have states CONNECT,DISCOONECT,SUSPEND(Host suspend for SDP cable),
> RESUME(Host wakeup), and UPDATE (to increase the charge
> current after USB enumaeration).Also the properties of the cable may
> vary based on the state. FOr example in SUSPENDED state platforms can
> support 0/100/500/950(USB 3.0) mA based on the HW. To initiate charging
> the consumer should be able to get the charger properties dynamically.
> 
> Signed-off-by: Jenny TC <jenny.tc@intel.com>
> ---
>  include/linux/extcon.h |   14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/include/linux/extcon.h b/include/linux/extcon.h
> index 073fd49..2e61ee0 100644
> --- a/include/linux/extcon.h
> +++ b/include/linux/extcon.h
> @@ -122,6 +122,7 @@ struct extcon_dev {
>  	/* --- Optional callbacks to override class functions --- */
>  	ssize_t	(*print_name)(struct extcon_dev *edev, char *buf);
>  	ssize_t	(*print_state)(struct extcon_dev *edev, char *buf);
> +	int (*get_cable_properties)(const char *cable_name, void *cable_props);
>  
>  	/* --- Internal data. Please do not set. --- */
>  	struct device	*dev;
> @@ -177,6 +178,19 @@ struct extcon_specific_cable_nb {
>  	unsigned long previous_value;
>  };
>  
> +enum extcon_chrgr_cbl_stat {
> +	EXTCON_CHRGR_CABLE_CONNECTED,
> +	EXTCON_CHRGR_CABLE_DISCONNECTED,
> +	EXTCON_CHRGR_CABLE_SUSPENDED,
> +	EXTCON_CHRGR_CABLE_RESUMED,
> +	EXTCON_CHRGR_CABLE_UPDATED,
> +};
I think the reason why we have extcon is in first place
is to only notify the clients of cable connection and
disconnection and it is up to the client to decide what
else to do with the cable such as finding which state it
is in and other details.
So I feel this should not be handled in the extcon.

However it is up to the maintainer to decide.
> +
> +struct extcon_chrgr_cbl_props {
> +	enum extcon_chrgr_cbl_stat cable_stat;
> +	unsigned long mA;
> +};
> +
>  #if IS_ENABLED(CONFIG_EXTCON)
>  
>  /*

RE: [PATCH] extcon : callback function to read cable property

[Tc, Jenny]

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> From: anish kumar [mailto:anish198519851985@gmail.com]
> Sent: Wednesday, October 10, 2012 8:15 PM
> To: Tc, Jenny
> Cc: myungjoo.ham@samsung.com; cw00.choi@samsung.com; linux-
> kernel@vger.kernel.org
> Subject: Re: [PATCH] extcon : callback function to read cable property
> 
> I think the reason why we have extcon is in first place is to only notify the
> clients of cable connection and disconnection and it is up to the client to
> decide what else to do with the cable such as finding which state it is in and
> other details.
> So I feel this should not be handled in the extcon.
> 
> However it is up to the maintainer to decide.

Once the consumer gets the notification, it needs to take some action. One of the action is to read the cable properties. This can be done by proprietary calls which is known both to the consumer and the provider. My intention is to avoid this proprietary calls. Since both the provider and consumer are communicating with the extcon subsystem , I feel having a callback function of this kind would help to avoid the use of proprietary calls. Also I agree that extcon notifier chains are used to notify the cable state (attach/detach). But if a cable has more than two states (like the charger cable) how do we support it without having a callback function like this? Let the maintainer take the final decision.


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RE: [PATCH] extcon : callback function to read cable property

[anish kumar]

On Thu, 2012-10-11 at 01:20 +0000, Tc, Jenny wrote:
> > From: anish kumar [mailto:anish198519851985@gmail.com]
> > Sent: Wednesday, October 10, 2012 8:15 PM
> > To: Tc, Jenny
> > Cc: myungjoo.ham@samsung.com; cw00.choi@samsung.com; linux-
> > kernel@vger.kernel.org
> > Subject: Re: [PATCH] extcon : callback function to read cable property
> > 
> > I think the reason why we have extcon is in first place is to only notify the
> > clients of cable connection and disconnection and it is up to the client to
> > decide what else to do with the cable such as finding which state it is in and
> > other details.
> > So I feel this should not be handled in the extcon.
> > 
> > However it is up to the maintainer to decide.
> 
> Once the consumer gets the notification, it needs to take some action. 
> One of the action is to read the cable properties. This can be done 
> by proprietary calls which is known both to the consumer and the provider. 
> My intention is to avoid this proprietary calls. Since both the provider 
> and consumer are communicating with the extcon subsystem , I feel having a 
> callback function of this kind would help to avoid the use of proprietary 
> calls. Also I agree that extcon notifier chains are used to notify the cable 
> state (attach/detach). But if a cable has more than two states (like the 
> charger cable) how do we support it without having a callback function like this? 
> Let the maintainer take the final decision.
Well this use case will keep on growing if we start factor in this kind
of changes and that is why I am opposed to adding any other state.
Maintainer?
> 
> 

RE: [PATCH] extcon : callback function to read cable property

[Tc, Jenny]

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Myunjoo/Chanwoo

Ping...
Could you please review this patch?

-jtc

> > > Subject: Re: [PATCH] extcon : callback function to read cable
> > > property
> > >
> > > I think the reason why we have extcon is in first place is to only
> > > notify the clients of cable connection and disconnection and it is
> > > up to the client to decide what else to do with the cable such as
> > > finding which state it is in and other details.
> > > So I feel this should not be handled in the extcon.
> > >
> > > However it is up to the maintainer to decide.
> >
> > Once the consumer gets the notification, it needs to take some action.
> > One of the action is to read the cable properties. This can be done by
> > proprietary calls which is known both to the consumer and the provider.
> > My intention is to avoid this proprietary calls. Since both the
> > provider and consumer are communicating with the extcon subsystem , I
> > feel having a callback function of this kind would help to avoid the
> > use of proprietary calls. Also I agree that extcon notifier chains are
> > used to notify the cable state (attach/detach). But if a cable has
> > more than two states (like the charger cable) how do we support it without
> having a callback function like this?
> > Let the maintainer take the final decision.
> Well this use case will keep on growing if we start factor in this kind of
> changes and that is why I am opposed to adding any other state.
> Maintainer?
> >
> >
> 

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Re: [PATCH] extcon : callback function to read cable property

[Chanwoo Choi]

On 10/17/2012 03:34 PM, Tc, Jenny wrote:
>>>> Subject: Re: [PATCH] extcon : callback function to read cable
>>>> property
>>>>
>>>> I think the reason why we have extcon is in first place is to only
>>>> notify the clients of cable connection and disconnection and it is
>>>> up to the client to decide what else to do with the cable such as
>>>> finding which state it is in and other details.
>>>> So I feel this should not be handled in the extcon.
>>>>
>>>> However it is up to the maintainer to decide.
>>>
>>> Once the consumer gets the notification, it needs to take some action.
>>> One of the action is to read the cable properties. This can be done by
>>> proprietary calls which is known both to the consumer and the provider.
>>> My intention is to avoid this proprietary calls. Since both the
>>> provider and consumer are communicating with the extcon subsystem , I
>>> feel having a callback function of this kind would help to avoid the
>>> use of proprietary calls. Also I agree that extcon notifier chains are
>>> used to notify the cable state (attach/detach). But if a cable has
>>> more than two states (like the charger cable) how do we support it without
>> having a callback function like this?
>>> Let the maintainer take the final decision.
>> Well this use case will keep on growing if we start factor in this kind of
>> changes and that is why I am opposed to adding any other state.
>> Maintainer?
>>>

I think that the role of extcon subsystem notify changed state(attached/detached)
of cable to notifiee, but if you want to add property feature of cable,
you should solve ambiguous issues.

First,
This patch only support the properties of charger cable but, never
support property of other cable. The following structure depend on
only charger cable. We can check it the following structure:
	struct extcon_chrg_cbl_props {
		enum extcon_chrgr_cbl_stat cable_state;
		unsigned long mA;
	};

I think that the patch have to support all of cables for property feature.

Second,
Certainly, you should define common properties of all cables and
specific properties of each cable. The properties of charger cable
should never be defined only.

Third,
If we finish to decide the properties for all cables, I'd like to see a example code.

You explained following changed state of USB according to Host state on other patch.
---------------------------
For USB2.0
1) CONNECT (100mA)->UPDATE(500mA)->DISCONNECT(0mA)
2) CONNECT (100mA)->UPDATE(500mA)->HOST SUSPEND(2.5mA/500mA)->DISCONNECT(0mA)
3) CONNECT (100mA)->UPDATE(500mA)->HOST SUSPEND(2.5mA/500mA)->HOST RESUME(500mA)->DISCONNECT(0mA)

For USB 3.0
4) CONNECT (150mA)->UPDATE(900mA)->DISCONNECT(0mA)
5) CONNECT (150mA)->UPDATE(900mA)-> HOST SUSPEND(2.5mA/900mA)->DISCONNECT(0mA)
6) CONNECT (100mA)->UPDATE(900mA)->HOST SUSPEND(2.5mA/900mA)->HOST RESUME(900mA)->DISCONNECT(0mA)
---------------------------

I have a question. Can the provider device driver(e.g., extcon-max77693.c/
extcon-max8997.c) detect the changed state of host? I'd like to see the
example device driver that the provider device driver detect changed state of host.
Could you provide example device driver?

Thanks,
Chanwoo Choi

RE: [PATCH] extcon : callback function to read cable property

[Tc, Jenny]

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> I think that the role of extcon subsystem notify changed
> state(attached/detached) of cable to notifiee, but if you want to add
> property feature of cable, you should solve ambiguous issues.
> 
> First,
> This patch only support the properties of charger cable but, never support
> property of other cable. The following structure depend on only charger
> cable. We can check it the following structure:
> 	struct extcon_chrg_cbl_props {
> 		enum extcon_chrgr_cbl_stat cable_state;
> 		unsigned long mA;
> 	};
> 
> I think that the patch have to support all of cables for property feature.

My suggestion is to have a structure like this 

struct  extcon_cablel_props {
	unsigned int cable_state;
    	unsigned int data; 
}

Not all cables will have more than two states. If any cable has more than two states,
the above structure makes it flexible to represent additional state and the data associated

> 
> Second,
> Certainly, you should define common properties of all cables and specific
> properties of each cable. The properties of charger cable should never be
> defined only.

Hope above structure would be enough to represent the common cable state and
it's data. If a cable has more than two states, then extcon_update_state can be used to
notify the consumer
1)Provider can just toggle the "state" argument to notify the consumer that cable state is 
changed
OR
2) Add one more argument  like  extcon_update_state(struct extcon_dev *edev, u32 mask, u32 state1, u32 sate2)
If the state2 is set, then consumers can use get_cable_properties() to query the cable properties. State2 need to be
used only if the cable need to represent more than two state

> 
> Third,
> If we finish to decide the properties for all cables, I'd like to see a example
> code.

Agreed. If we  agree on the above structure, I can modify the charging subsystem patch
to use the same structure. (https://lkml.org/lkml/2012/10/18/219). This would give a reference
for the new feature.

> 
> You explained following changed state of USB according to Host state on
> other patch.
> ---------------------------
> For USB2.0
> 1) CONNECT (100mA)->UPDATE(500mA)->DISCONNECT(0mA)
> 2) CONNECT (100mA)->UPDATE(500mA)->HOST SUSPEND(2.5mA/500mA)-
> >DISCONNECT(0mA)
> 3) CONNECT (100mA)->UPDATE(500mA)->HOST SUSPEND(2.5mA/500mA)-
> >HOST RESUME(500mA)->DISCONNECT(0mA)
> 
> For USB 3.0
> 4) CONNECT (150mA)->UPDATE(900mA)->DISCONNECT(0mA)
> 5) CONNECT (150mA)->UPDATE(900mA)-> HOST SUSPEND(2.5mA/900mA)-
> >DISCONNECT(0mA)
> 6) CONNECT (100mA)->UPDATE(900mA)->HOST SUSPEND(2.5mA/900mA)-
> >HOST RESUME(900mA)->DISCONNECT(0mA)
> ---------------------------
> 
> I have a question. Can the provider device driver(e.g., extcon-max77693.c/
> extcon-max8997.c) detect the changed state of host? I'd like to see the
> example device driver that the provider device driver detect changed state
> of host.
> Could you provide example device driver?

Good question. The OTG drivers are capable of identifying the SUSPEND event.
System cannot setup SDP (USB host) charging with maximum charging current - 500mA
(USB2.0/ 900mA(USB 3)) without enumerating the USB. The USB enumeration can be
done only with a USB/OTG driver. IMHO the above extcon drivers
(extcon-max77693.c/ extcon-max8997.c) are not capable of doing the USB enumeration
and identifying the charge current. They can just identify the charger type - 
SDP/DCP/CDP/ACA/AC. The intelligence for USB enumeration 
should be inside USB/OTG driver.

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RE: [PATCH] extcon : callback function to read cable property

[anish kumar]

On Fri, 2012-11-09 at 14:05 +0000, Tc, Jenny wrote:
> > I think that the role of extcon subsystem notify changed
> > state(attached/detached) of cable to notifiee, but if you want to add
> > property feature of cable, you should solve ambiguous issues.
> > 
> > First,
> > This patch only support the properties of charger cable but, never support
> > property of other cable. The following structure depend on only charger
> > cable. We can check it the following structure:
> > 	struct extcon_chrg_cbl_props {
> > 		enum extcon_chrgr_cbl_stat cable_state;
> > 		unsigned long mA;
> > 	};
> > 
> > I think that the patch have to support all of cables for property feature.
> 
> My suggestion is to have a structure like this 
> 
> struct  extcon_cablel_props {
> 	unsigned int cable_state;
>     	unsigned int data; 
Why can't it be float/long/double??
> }
> Not all cables will have more than two states. If any cable has more than two states,
> the above structure makes it flexible to represent additional state and the data associated
> 
> > 
> > Second,
> > Certainly, you should define common properties of all cables and specific
> > properties of each cable. The properties of charger cable should never be
> > defined only.
IMHO the extcon doesn't know anything about the cable except the state
which is currently it is in and which also is set by the provider.I am
unable to understand why should extcon provide more than what it
knows?It should just limit itself to broadcasting the cable state and
exploiting it for any other information would only lead to more
un-necessary code.
It should be same as IIO subsystem where the consumer and provider knows
before hand what information they are going to share and with what
precision and IIO core is just a way to do that.It doesn't know anything
beyond what is given by the provider.
Same is the case with driver core where individual driver sets it's own
private data and the driver core just gives that private data back to
the driver as and when it needs but parsing the private data in the
right way is up to the individual driver.

I fail to understand why is not the case here. 
> 
> Hope above structure would be enough to represent the common cable state and
> it's data. If a cable has more than two states, then extcon_update_state can be used to
> notify the consumer
> 1)Provider can just toggle the "state" argument to notify the consumer that cable state is 
> changed
> OR
> 2) Add one more argument  like  extcon_update_state(struct extcon_dev *edev, u32 mask, u32 state1, u32 sate2)
This will cause other drivers to change such as arizona.
> If the state2 is set, then consumers can use get_cable_properties() to query the cable properties. State2 need to be
> used only if the cable need to represent more than two state
> 
> > 
> > Third,
> > If we finish to decide the properties for all cables, I'd like to see a example
Why do we think that state and property is the only thing which the
consumer want to know?I am sure there would be some more properties
which would be of some interest to consumers and there is quite a
possibility that in future we might get a patch for that also.So instead
of that limiting it to just state is a good idea.
> > code.
> 
> Agreed. If we  agree on the above structure, I can modify the charging subsystem patch
> to use the same structure. (https://lkml.org/lkml/2012/10/18/219). This would give a reference
> for the new feature.
> 
> > 
> > You explained following changed state of USB according to Host state on
> > other patch.
> > ---------------------------
> > For USB2.0
> > 1) CONNECT (100mA)->UPDATE(500mA)->DISCONNECT(0mA)
> > 2) CONNECT (100mA)->UPDATE(500mA)->HOST SUSPEND(2.5mA/500mA)-
> > >DISCONNECT(0mA)
> > 3) CONNECT (100mA)->UPDATE(500mA)->HOST SUSPEND(2.5mA/500mA)-
> > >HOST RESUME(500mA)->DISCONNECT(0mA)
> > 
> > For USB 3.0
> > 4) CONNECT (150mA)->UPDATE(900mA)->DISCONNECT(0mA)
> > 5) CONNECT (150mA)->UPDATE(900mA)-> HOST SUSPEND(2.5mA/900mA)-
> > >DISCONNECT(0mA)
> > 6) CONNECT (100mA)->UPDATE(900mA)->HOST SUSPEND(2.5mA/900mA)-
> > >HOST RESUME(900mA)->DISCONNECT(0mA)
> > ---------------------------
> > 
> > I have a question. Can the provider device driver(e.g., extcon-max77693.c/
> > extcon-max8997.c) detect the changed state of host? I'd like to see the
> > example device driver that the provider device driver detect changed state
> > of host.
> > Could you provide example device driver?
> 
> Good question. The OTG drivers are capable of identifying the SUSPEND event.
> System cannot setup SDP (USB host) charging with maximum charging current - 500mA
> (USB2.0/ 900mA(USB 3)) without enumerating the USB. The USB enumeration can be
> done only with a USB/OTG driver. IMHO the above extcon drivers
> (extcon-max77693.c/ extcon-max8997.c) are not capable of doing the USB enumeration
> and identifying the charge current. They can just identify the charger type - 
> SDP/DCP/CDP/ACA/AC. The intelligence for USB enumeration 
> should be inside USB/OTG driver.
> 

RE: [PATCH] extcon : callback function to read cable property

[Tc, Jenny]

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> > > I think that the role of extcon subsystem notify changed
> > > state(attached/detached) of cable to notifiee, but if you want to
> > > add property feature of cable, you should solve ambiguous issues.
> > >
> > > First,
> > > This patch only support the properties of charger cable but, never
> > > support property of other cable. The following structure depend on
> > > only charger cable. We can check it the following structure:
> > > 	struct extcon_chrg_cbl_props {
> > > 		enum extcon_chrgr_cbl_stat cable_state;
> > > 		unsigned long mA;
> > > 	};
> > >
> > > I think that the patch have to support all of cables for property feature.
> >
> > My suggestion is to have a structure like this
> >
> > struct  extcon_cablel_props {
> > 	unsigned int cable_state;
> >     	unsigned int data;
> Why can't it be float/long/double??
> > }
> > Not all cables will have more than two states. If any cable has more
> > than two states, the above structure makes it flexible to represent
> > additional state and the data associated
> >
> > >
> > > Second,
> > > Certainly, you should define common properties of all cables and
> > > specific properties of each cable. The properties of charger cable
> > > should never be defined only.
> IMHO the extcon doesn't know anything about the cable except the state
> which is currently it is in and which also is set by the provider.I am unable to
> understand why should extcon provide more than what it knows?It should
> just limit itself to broadcasting the cable state and exploiting it for any other
> information would only lead to more un-necessary code.
> It should be same as IIO subsystem where the consumer and provider knows
> before hand what information they are going to share and with what
> precision and IIO core is just a way to do that.It doesn't know anything
> beyond what is given by the provider.
> Same is the case with driver core where individual driver sets it's own private
> data and the driver core just gives that private data back to the driver as and
> when it needs but parsing the private data in the right way is up to the
> individual driver.
> 
> I fail to understand why is not the case here.

The requirement is different from the IIO case. I am trying to extend the Power Supply
class to support charging in a generic way (https://lkml.org/lkml/2012/10/18/219).
The extcon consumer in this case is not a device driver. It's part of power supply class driver itself.
I am open to any solution to get the cable properties dynamically. Do you find a better
but generic mechanism for this?

I am trying to extend  extcon just because I couldn’t find any other subsystem which gives
cable notifications. IMHO, it's good if we can avoid consumer and provider driver level
dependencies just by extending extcon. This will ensure that the same driver
will work on any platform as long as it's having the dependency only on extcon. 
We shouldn't put any driver level dependency between extcon consumer and provider.
When we do like that, the extcon consumer is expecting the
similar implementation for the provider on all platforms. This may not be possible
and does not seems to  be a scalable solution. IMHO, the extcon should provide a mechanism to retrieve
the cable properties. Consumer drivers can use this API to get the cable properties without
knowing the provider driver implementation. This will  make the extcon drivers more scalable
and reusable across multiple platforms.

> >
> > Hope above structure would be enough to represent the common cable
> > state and it's data. If a cable has more than two states, then
> > extcon_update_state can be used to notify the consumer 1)Provider can
> > just toggle the "state" argument to notify the consumer that cable
> > state is changed OR
> > 2) Add one more argument  like  extcon_update_state(struct extcon_dev
> > *edev, u32 mask, u32 state1, u32 sate2)
> This will cause other drivers to change such as arizona.
> > If the state2 is set, then consumers can use get_cable_properties() to
> > query the cable properties. State2 need to be used only if the cable
> > need to represent more than two state
> >
> > >
> > > Third,
> > > If we finish to decide the properties for all cables, I'd like to
> > > see a example
> Why do we think that state and property is the only thing which the
> consumer want to know?I am sure there would be some more properties
> which would be of some interest to consumers and there is quite a possibility
> that in future we might get a patch for that also.So instead of that limiting it
> to just state is a good idea.
> > > code.
> >
> > Agreed. If we  agree on the above structure, I can modify the charging
> > subsystem patch to use the same structure.
> > (https://lkml.org/lkml/2012/10/18/219). This would give a reference for the
> new feature.
> >
> > >
> > > You explained following changed state of USB according to Host state
> > > on other patch.
> > > ---------------------------
> > > For USB2.0
> > > 1) CONNECT (100mA)->UPDATE(500mA)->DISCONNECT(0mA)
> > > 2) CONNECT (100mA)->UPDATE(500mA)->HOST
> SUSPEND(2.5mA/500mA)-
> > > >DISCONNECT(0mA)
> > > 3) CONNECT (100mA)->UPDATE(500mA)->HOST
> SUSPEND(2.5mA/500mA)-
> > > >HOST RESUME(500mA)->DISCONNECT(0mA)
> > >
> > > For USB 3.0
> > > 4) CONNECT (150mA)->UPDATE(900mA)->DISCONNECT(0mA)
> > > 5) CONNECT (150mA)->UPDATE(900mA)-> HOST
> SUSPEND(2.5mA/900mA)-
> > > >DISCONNECT(0mA)
> > > 6) CONNECT (100mA)->UPDATE(900mA)->HOST
> SUSPEND(2.5mA/900mA)-
> > > >HOST RESUME(900mA)->DISCONNECT(0mA)
> > > ---------------------------
> > >
> > > I have a question. Can the provider device driver(e.g.,
> > > extcon-max77693.c/
> > > extcon-max8997.c) detect the changed state of host? I'd like to see
> > > the example device driver that the provider device driver detect
> > > changed state of host.
> > > Could you provide example device driver?
> >
> > Good question. The OTG drivers are capable of identifying the SUSPEND
> event.
> > System cannot setup SDP (USB host) charging with maximum charging
> > current - 500mA (USB2.0/ 900mA(USB 3)) without enumerating the USB.
> > The USB enumeration can be done only with a USB/OTG driver. IMHO the
> > above extcon drivers (extcon-max77693.c/ extcon-max8997.c) are not
> > capable of doing the USB enumeration and identifying the charge
> > current. They can just identify the charger type - SDP/DCP/CDP/ACA/AC.
> > The intelligence for USB enumeration should be inside USB/OTG driver.
> >
> 

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Re: [PATCH] extcon : callback function to read cable property

[anish singh]

On Wed, Nov 14, 2012 at 8:05 PM, Tc, Jenny <jenny.tc@intel.com> wrote:
>
>
>> > > I think that the role of extcon subsystem notify changed
>> > > state(attached/detached) of cable to notifiee, but if you want to
>> > > add property feature of cable, you should solve ambiguous issues.
>> > >
>> > > First,
>> > > This patch only support the properties of charger cable but, never
>> > > support property of other cable. The following structure depend on
>> > > only charger cable. We can check it the following structure:
>> > >   struct extcon_chrg_cbl_props {
>> > >           enum extcon_chrgr_cbl_stat cable_state;
>> > >           unsigned long mA;
>> > >   };
>> > >
>> > > I think that the patch have to support all of cables for property feature.
>> >
>> > My suggestion is to have a structure like this
>> >
>> > struct  extcon_cablel_props {
>> >     unsigned int cable_state;
>> >             unsigned int data;
>> Why can't it be float/long/double??
>> > }
>> > Not all cables will have more than two states. If any cable has more
>> > than two states, the above structure makes it flexible to represent
>> > additional state and the data associated
>> >
>> > >
>> > > Second,
>> > > Certainly, you should define common properties of all cables and
>> > > specific properties of each cable. The properties of charger cable
>> > > should never be defined only.
>> IMHO the extcon doesn't know anything about the cable except the state
>> which is currently it is in and which also is set by the provider.I am unable to
>> understand why should extcon provide more than what it knows?It should
>> just limit itself to broadcasting the cable state and exploiting it for any other
>> information would only lead to more un-necessary code.
>> It should be same as IIO subsystem where the consumer and provider knows
>> before hand what information they are going to share and with what
>> precision and IIO core is just a way to do that.It doesn't know anything
>> beyond what is given by the provider.
>> Same is the case with driver core where individual driver sets it's own private
>> data and the driver core just gives that private data back to the driver as and
>> when it needs but parsing the private data in the right way is up to the
>> individual driver.
>>
>> I fail to understand why is not the case here.
>
> The requirement is different from the IIO case. I am trying to extend the Power Supply
> class to support charging in a generic way (https://lkml.org/lkml/2012/10/18/219).
> The extcon consumer in this case is not a device driver. It's part of power supply class driver itself.
> I am open to any solution to get the cable properties dynamically. Do you find a better
> but generic mechanism for this?
>
> I am trying to extend  extcon just because I couldn’t find any other subsystem which gives
> cable notifications. IMHO, it's good if we can avoid consumer and provider driver level
> dependencies just by extending extcon. This will ensure that the same driver
> will work on any platform as long as it's having the dependency only on extcon.
> We shouldn't put any driver level dependency between extcon consumer and provider.
> When we do like that, the extcon consumer is expecting the
> similar implementation for the provider on all platforms. This may not be possible
Is there anything wrong in assuming similar implementation for all the
providers?I think the
providers know what it can provide and this may vary quite a lot.Or
can we make a generic provider
driver which will encompass all the randomness in the various provider
drivers?This generic
driver will get all the properties and since it will be generice
anyone can use it to know what
properties to expect.This will keep the extcon design intact.

> and does not seems to  be a scalable solution. IMHO, the extcon should provide a mechanism to retrieve
> the cable properties. Consumer drivers can use this API to get the cable properties without
> knowing the provider driver implementation. This will  make the extcon drivers more scalable
> and reusable across multiple platforms.
>
>> >
>> > Hope above structure would be enough to represent the common cable
>> > state and it's data. If a cable has more than two states, then
>> > extcon_update_state can be used to notify the consumer 1)Provider can
>> > just toggle the "state" argument to notify the consumer that cable
>> > state is changed OR
>> > 2) Add one more argument  like  extcon_update_state(struct extcon_dev
>> > *edev, u32 mask, u32 state1, u32 sate2)
>> This will cause other drivers to change such as arizona.
>> > If the state2 is set, then consumers can use get_cable_properties() to
>> > query the cable properties. State2 need to be used only if the cable
>> > need to represent more than two state
>> >
>> > >
>> > > Third,
>> > > If we finish to decide the properties for all cables, I'd like to
>> > > see a example
>> Why do we think that state and property is the only thing which the
>> consumer want to know?I am sure there would be some more properties
>> which would be of some interest to consumers and there is quite a possibility
>> that in future we might get a patch for that also.So instead of that limiting it
>> to just state is a good idea.
>> > > code.
>> >
>> > Agreed. If we  agree on the above structure, I can modify the charging
>> > subsystem patch to use the same structure.
>> > (https://lkml.org/lkml/2012/10/18/219). This would give a reference for the
>> new feature.
>> >
>> > >
>> > > You explained following changed state of USB according to Host state
>> > > on other patch.
>> > > ---------------------------
>> > > For USB2.0
>> > > 1) CONNECT (100mA)->UPDATE(500mA)->DISCONNECT(0mA)
>> > > 2) CONNECT (100mA)->UPDATE(500mA)->HOST
>> SUSPEND(2.5mA/500mA)-
>> > > >DISCONNECT(0mA)
>> > > 3) CONNECT (100mA)->UPDATE(500mA)->HOST
>> SUSPEND(2.5mA/500mA)-
>> > > >HOST RESUME(500mA)->DISCONNECT(0mA)
>> > >
>> > > For USB 3.0
>> > > 4) CONNECT (150mA)->UPDATE(900mA)->DISCONNECT(0mA)
>> > > 5) CONNECT (150mA)->UPDATE(900mA)-> HOST
>> SUSPEND(2.5mA/900mA)-
>> > > >DISCONNECT(0mA)
>> > > 6) CONNECT (100mA)->UPDATE(900mA)->HOST
>> SUSPEND(2.5mA/900mA)-
>> > > >HOST RESUME(900mA)->DISCONNECT(0mA)
>> > > ---------------------------
>> > >
>> > > I have a question. Can the provider device driver(e.g.,
>> > > extcon-max77693.c/
>> > > extcon-max8997.c) detect the changed state of host? I'd like to see
>> > > the example device driver that the provider device driver detect
>> > > changed state of host.
>> > > Could you provide example device driver?
>> >
>> > Good question. The OTG drivers are capable of identifying the SUSPEND
>> event.
>> > System cannot setup SDP (USB host) charging with maximum charging
>> > current - 500mA (USB2.0/ 900mA(USB 3)) without enumerating the USB.
>> > The USB enumeration can be done only with a USB/OTG driver. IMHO the
>> > above extcon drivers (extcon-max77693.c/ extcon-max8997.c) are not
>> > capable of doing the USB enumeration and identifying the charge
>> > current. They can just identify the charger type - SDP/DCP/CDP/ACA/AC.
>> > The intelligence for USB enumeration should be inside USB/OTG driver.
>> >
>>
>

RE: [PATCH] extcon : callback function to read cable property

[Tc, Jenny]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset="utf-8", Size: 7599 bytes --]

> >> > > I think that the role of extcon subsystem notify changed
> >> > > state(attached/detached) of cable to notifiee, but if you want to
> >> > > add property feature of cable, you should solve ambiguous issues.
> >> > >
> >> > > First,
> >> > > This patch only support the properties of charger cable but,
> >> > > never support property of other cable. The following structure
> >> > > depend on only charger cable. We can check it the following structure:
> >> > >   struct extcon_chrg_cbl_props {
> >> > >           enum extcon_chrgr_cbl_stat cable_state;
> >> > >           unsigned long mA;
> >> > >   };
> >> > >
> >> > > I think that the patch have to support all of cables for property
> feature.
> >> >
> >> > My suggestion is to have a structure like this
> >> >
> >> > struct  extcon_cablel_props {
> >> >     unsigned int cable_state;
> >> >             unsigned int data;
> >> Why can't it be float/long/double??
> >> > }
> >> > Not all cables will have more than two states. If any cable has
> >> > more than two states, the above structure makes it flexible to
> >> > represent additional state and the data associated
> >> >
> >> > >
> >> > > Second,
> >> > > Certainly, you should define common properties of all cables and
> >> > > specific properties of each cable. The properties of charger
> >> > > cable should never be defined only.
> >> IMHO the extcon doesn't know anything about the cable except the
> >> state which is currently it is in and which also is set by the
> >> provider.I am unable to understand why should extcon provide more
> >> than what it knows?It should just limit itself to broadcasting the
> >> cable state and exploiting it for any other information would only lead to
> more un-necessary code.
> >> It should be same as IIO subsystem where the consumer and provider
> >> knows before hand what information they are going to share and with
> >> what precision and IIO core is just a way to do that.It doesn't know
> >> anything beyond what is given by the provider.
> >> Same is the case with driver core where individual driver sets it's
> >> own private data and the driver core just gives that private data
> >> back to the driver as and when it needs but parsing the private data
> >> in the right way is up to the individual driver.
> >>
> >> I fail to understand why is not the case here.
> >
> > The requirement is different from the IIO case. I am trying to extend
> > the Power Supply class to support charging in a generic way
> (https://lkml.org/lkml/2012/10/18/219).
> > The extcon consumer in this case is not a device driver. It's part of power
> supply class driver itself.
> > I am open to any solution to get the cable properties dynamically. Do
> > you find a better but generic mechanism for this?
> >
> > I am trying to extend  extcon just because I couldn’t find any other
> > subsystem which gives cable notifications. IMHO, it's good if we can
> > avoid consumer and provider driver level dependencies just by
> > extending extcon. This will ensure that the same driver will work on any
> platform as long as it's having the dependency only on extcon.
> > We shouldn't put any driver level dependency between extcon consumer
> and provider.
> > When we do like that, the extcon consumer is expecting the similar
> > implementation for the provider on all platforms. This may not be
> > possible
> Is there anything wrong in assuming similar implementation for all the
> providers?I think the providers know what it can provide and this may vary
> quite a lot.Or can we make a generic provider driver which will encompass all
> the randomness in the various provider drivers?This generic driver will get all
> the properties and since it will be generice anyone can use it to know what
> properties to expect.This will keep the extcon design intact.

Maintainer??

> 
> > and does not seems to  be a scalable solution. IMHO, the extcon should
> > provide a mechanism to retrieve the cable properties. Consumer drivers
> > can use this API to get the cable properties without knowing the
> > provider driver implementation. This will  make the extcon drivers more
> scalable and reusable across multiple platforms.
> >
> >> >
> >> > Hope above structure would be enough to represent the common cable
> >> > state and it's data. If a cable has more than two states, then
> >> > extcon_update_state can be used to notify the consumer 1)Provider
> >> > can just toggle the "state" argument to notify the consumer that
> >> > cable state is changed OR
> >> > 2) Add one more argument  like  extcon_update_state(struct
> >> > extcon_dev *edev, u32 mask, u32 state1, u32 sate2)
> >> This will cause other drivers to change such as arizona.
> >> > If the state2 is set, then consumers can use get_cable_properties()
> >> > to query the cable properties. State2 need to be used only if the
> >> > cable need to represent more than two state
> >> >
> >> > >
> >> > > Third,
> >> > > If we finish to decide the properties for all cables, I'd like to
> >> > > see a example
> >> Why do we think that state and property is the only thing which the
> >> consumer want to know?I am sure there would be some more properties
> >> which would be of some interest to consumers and there is quite a
> >> possibility that in future we might get a patch for that also.So
> >> instead of that limiting it to just state is a good idea.
> >> > > code.
> >> >
> >> > Agreed. If we  agree on the above structure, I can modify the
> >> > charging subsystem patch to use the same structure.
> >> > (https://lkml.org/lkml/2012/10/18/219). This would give a reference
> >> > for the
> >> new feature.
> >> >
> >> > >
> >> > > You explained following changed state of USB according to Host
> >> > > state on other patch.
> >> > > ---------------------------
> >> > > For USB2.0
> >> > > 1) CONNECT (100mA)->UPDATE(500mA)->DISCONNECT(0mA)
> >> > > 2) CONNECT (100mA)->UPDATE(500mA)->HOST
> >> SUSPEND(2.5mA/500mA)-
> >> > > >DISCONNECT(0mA)
> >> > > 3) CONNECT (100mA)->UPDATE(500mA)->HOST
> >> SUSPEND(2.5mA/500mA)-
> >> > > >HOST RESUME(500mA)->DISCONNECT(0mA)
> >> > >
> >> > > For USB 3.0
> >> > > 4) CONNECT (150mA)->UPDATE(900mA)->DISCONNECT(0mA)
> >> > > 5) CONNECT (150mA)->UPDATE(900mA)-> HOST
> >> SUSPEND(2.5mA/900mA)-
> >> > > >DISCONNECT(0mA)
> >> > > 6) CONNECT (100mA)->UPDATE(900mA)->HOST
> >> SUSPEND(2.5mA/900mA)-
> >> > > >HOST RESUME(900mA)->DISCONNECT(0mA)
> >> > > ---------------------------
> >> > >
> >> > > I have a question. Can the provider device driver(e.g.,
> >> > > extcon-max77693.c/
> >> > > extcon-max8997.c) detect the changed state of host? I'd like to
> >> > > see the example device driver that the provider device driver
> >> > > detect changed state of host.
> >> > > Could you provide example device driver?
> >> >
> >> > Good question. The OTG drivers are capable of identifying the
> >> > SUSPEND
> >> event.
> >> > System cannot setup SDP (USB host) charging with maximum charging
> >> > current - 500mA (USB2.0/ 900mA(USB 3)) without enumerating the USB.
> >> > The USB enumeration can be done only with a USB/OTG driver. IMHO
> >> > the above extcon drivers (extcon-max77693.c/ extcon-max8997.c) are
> >> > not capable of doing the USB enumeration and identifying the charge
> >> > current. They can just identify the charger type -
> SDP/DCP/CDP/ACA/AC.
> >> > The intelligence for USB enumeration should be inside USB/OTG driver.
> >> >
> >>
> >
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Re: [PATCH] extcon : callback function to read cable property

[Chanwoo Choi]

On 11/20/2012 10:39 AM, Tc, Jenny wrote:
>>>>>> I think that the role of extcon subsystem notify changed
>>>>>> state(attached/detached) of cable to notifiee, but if you want to
>>>>>> add property feature of cable, you should solve ambiguous issues.
>>>>>>
>>>>>> First,
>>>>>> This patch only support the properties of charger cable but,
>>>>>> never support property of other cable. The following structure
>>>>>> depend on only charger cable. We can check it the following structure:
>>>>>>   struct extcon_chrg_cbl_props {
>>>>>>           enum extcon_chrgr_cbl_stat cable_state;
>>>>>>           unsigned long mA;
>>>>>>   };
>>>>>>
>>>>>> I think that the patch have to support all of cables for property
>> feature.
>>>>>
>>>>> My suggestion is to have a structure like this
>>>>>
>>>>> struct  extcon_cablel_props {
>>>>>     unsigned int cable_state;
>>>>>             unsigned int data;
>>>> Why can't it be float/long/double??
>>>>> }
>>>>> Not all cables will have more than two states. If any cable has
>>>>> more than two states, the above structure makes it flexible to
>>>>> represent additional state and the data associated
>>>>>
>>>>>>
>>>>>> Second,
>>>>>> Certainly, you should define common properties of all cables and
>>>>>> specific properties of each cable. The properties of charger
>>>>>> cable should never be defined only.
>>>> IMHO the extcon doesn't know anything about the cable except the
>>>> state which is currently it is in and which also is set by the
>>>> provider.I am unable to understand why should extcon provide more
>>>> than what it knows?It should just limit itself to broadcasting the
>>>> cable state and exploiting it for any other information would only lead to
>> more un-necessary code.
>>>> It should be same as IIO subsystem where the consumer and provider
>>>> knows before hand what information they are going to share and with
>>>> what precision and IIO core is just a way to do that.It doesn't know
>>>> anything beyond what is given by the provider.
>>>> Same is the case with driver core where individual driver sets it's
>>>> own private data and the driver core just gives that private data
>>>> back to the driver as and when it needs but parsing the private data
>>>> in the right way is up to the individual driver.
>>>>
>>>> I fail to understand why is not the case here.
>>>
>>> The requirement is different from the IIO case. I am trying to extend
>>> the Power Supply class to support charging in a generic way
>> (https://lkml.org/lkml/2012/10/18/219).
>>> The extcon consumer in this case is not a device driver. It's part of power
>> supply class driver itself.
>>> I am open to any solution to get the cable properties dynamically. Do
>>> you find a better but generic mechanism for this?
>>>
>>> I am trying to extend  extcon just because I couldn’t find any other
>>> subsystem which gives cable notifications. IMHO, it's good if we can
>>> avoid consumer and provider driver level dependencies just by
>>> extending extcon. This will ensure that the same driver will work on any
>> platform as long as it's having the dependency only on extcon.
>>> We shouldn't put any driver level dependency between extcon consumer
>> and provider.
>>> When we do like that, the extcon consumer is expecting the similar
>>> implementation for the provider on all platforms. This may not be
>>> possible
>> Is there anything wrong in assuming similar implementation for all the
>> providers?I think the providers know what it can provide and this may vary
>> quite a lot.Or can we make a generic provider driver which will encompass all
>> the randomness in the various provider drivers?This generic driver will get all
>> the properties and since it will be generice anyone can use it to know what
>> properties to expect.This will keep the extcon design intact.
> 
> Maintainer??

I agreed about opinion of anish singh. The extcon provider driver provide generic

----
struct  extcon_cablel_props {
     unsigned int cable_state;
     unsigned int data;
}
----
You suggested upper structure and said it is only flexible to represent additional state,
But, it is non-standard. What store real data on "unsigned int data"? It isn't determined
and flexible. That is extcon consumer driver should already know type of real data or
value of real data. The extcon consumer driver has strong dependency on extcon provider
driver. In this case, if extcon provider driver can change data value of "unsigned int data",
extcon consumer provider have to be modified according to extcon provider driver.
I think it isn't correct apporach. So, I proposed that we should define properties for all cables.

>>
>>> and does not seems to  be a scalable solution. IMHO, the extcon should
>>> provide a mechanism to retrieve the cable properties. Consumer drivers
>>> can use this API to get the cable properties without knowing the
>>> provider driver implementation. This will  make the extcon drivers more
>> scalable and reusable across multiple platforms.
>>>
>>>>>
>>>>> Hope above structure would be enough to represent the common cable
>>>>> state and it's data. If a cable has more than two states, then
>>>>> extcon_update_state can be used to notify the consumer 1)Provider
>>>>> can just toggle the "state" argument to notify the consumer that
>>>>> cable state is changed OR
>>>>> 2) Add one more argument  like  extcon_update_state(struct
>>>>> extcon_dev *edev, u32 mask, u32 state1, u32 sate2)
>>>> This will cause other drivers to change such as arizona.
>>>>> If the state2 is set, then consumers can use get_cable_properties()
>>>>> to query the cable properties. State2 need to be used only if the
>>>>> cable need to represent more than two state
>>>>>
>>>>>>
>>>>>> Third,
>>>>>> If we finish to decide the properties for all cables, I'd like to
>>>>>> see a example
>>>> Why do we think that state and property is the only thing which the
>>>> consumer want to know?I am sure there would be some more properties
>>>> which would be of some interest to consumers and there is quite a
>>>> possibility that in future we might get a patch for that also.So
>>>> instead of that limiting it to just state is a good idea.
>>>>>> code.
>>>>>
>>>>> Agreed. If we  agree on the above structure, I can modify the
>>>>> charging subsystem patch to use the same structure.
>>>>> (https://lkml.org/lkml/2012/10/18/219). This would give a reference
>>>>> for the
>>>> new feature.
>>>>>
>>>>>>
>>>>>> You explained following changed state of USB according to Host
>>>>>> state on other patch.
>>>>>> ---------------------------
>>>>>> For USB2.0
>>>>>> 1) CONNECT (100mA)->UPDATE(500mA)->DISCONNECT(0mA)
>>>>>> 2) CONNECT (100mA)->UPDATE(500mA)->HOST
>>>> SUSPEND(2.5mA/500mA)-
>>>>>>> DISCONNECT(0mA)
>>>>>> 3) CONNECT (100mA)->UPDATE(500mA)->HOST
>>>> SUSPEND(2.5mA/500mA)-
>>>>>>> HOST RESUME(500mA)->DISCONNECT(0mA)
>>>>>>
>>>>>> For USB 3.0
>>>>>> 4) CONNECT (150mA)->UPDATE(900mA)->DISCONNECT(0mA)
>>>>>> 5) CONNECT (150mA)->UPDATE(900mA)-> HOST
>>>> SUSPEND(2.5mA/900mA)-
>>>>>>> DISCONNECT(0mA)
>>>>>> 6) CONNECT (100mA)->UPDATE(900mA)->HOST
>>>> SUSPEND(2.5mA/900mA)-
>>>>>>> HOST RESUME(900mA)->DISCONNECT(0mA)
>>>>>> ---------------------------
>>>>>>
>>>>>> I have a question. Can the provider device driver(e.g.,
>>>>>> extcon-max77693.c/
>>>>>> extcon-max8997.c) detect the changed state of host? I'd like to
>>>>>> see the example device driver that the provider device driver
>>>>>> detect changed state of host.
>>>>>> Could you provide example device driver?
>>>>>
>>>>> Good question. The OTG drivers are capable of identifying the
>>>>> SUSPEND
>>>> event.
>>>>> System cannot setup SDP (USB host) charging with maximum charging
>>>>> current - 500mA (USB2.0/ 900mA(USB 3)) without enumerating the USB.
>>>>> The USB enumeration can be done only with a USB/OTG driver. IMHO
>>>>> the above extcon drivers (extcon-max77693.c/ extcon-max8997.c) are
>>>>> not capable of doing the USB enumeration and identifying the charge
>>>>> current. They can just identify the charger type -
>> SDP/DCP/CDP/ACA/AC.
>>>>> The intelligence for USB enumeration should be inside USB/OTG driver.

RE: [PATCH] extcon : callback function to read cable property

[Tc, Jenny]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset="utf-8", Size: 9085 bytes --]

> >>>>>> I think that the role of extcon subsystem notify changed
> >>>>>> state(attached/detached) of cable to notifiee, but if you want to
> >>>>>> add property feature of cable, you should solve ambiguous issues.
> >>>>>>
> >>>>>> First,
> >>>>>> This patch only support the properties of charger cable but,
> >>>>>> never support property of other cable. The following structure
> >>>>>> depend on only charger cable. We can check it the following
> structure:
> >>>>>>   struct extcon_chrg_cbl_props {
> >>>>>>           enum extcon_chrgr_cbl_stat cable_state;
> >>>>>>           unsigned long mA;
> >>>>>>   };
> >>>>>>
> >>>>>> I think that the patch have to support all of cables for property
> >> feature.
> >>>>>
> >>>>> My suggestion is to have a structure like this
> >>>>>
> >>>>> struct  extcon_cablel_props {
> >>>>>     unsigned int cable_state;
> >>>>>             unsigned int data;
> >>>> Why can't it be float/long/double??
> >>>>> }
> >>>>> Not all cables will have more than two states. If any cable has
> >>>>> more than two states, the above structure makes it flexible to
> >>>>> represent additional state and the data associated
> >>>>>
> >>>>>>
> >>>>>> Second,
> >>>>>> Certainly, you should define common properties of all cables and
> >>>>>> specific properties of each cable. The properties of charger
> >>>>>> cable should never be defined only.
> >>>> IMHO the extcon doesn't know anything about the cable except the
> >>>> state which is currently it is in and which also is set by the
> >>>> provider.I am unable to understand why should extcon provide more
> >>>> than what it knows?It should just limit itself to broadcasting the
> >>>> cable state and exploiting it for any other information would only
> >>>> lead to
> >> more un-necessary code.
> >>>> It should be same as IIO subsystem where the consumer and provider
> >>>> knows before hand what information they are going to share and with
> >>>> what precision and IIO core is just a way to do that.It doesn't
> >>>> know anything beyond what is given by the provider.
> >>>> Same is the case with driver core where individual driver sets it's
> >>>> own private data and the driver core just gives that private data
> >>>> back to the driver as and when it needs but parsing the private
> >>>> data in the right way is up to the individual driver.
> >>>>
> >>>> I fail to understand why is not the case here.
> >>>
> >>> The requirement is different from the IIO case. I am trying to
> >>> extend the Power Supply class to support charging in a generic way
> >> (https://lkml.org/lkml/2012/10/18/219).
> >>> The extcon consumer in this case is not a device driver. It's part
> >>> of power
> >> supply class driver itself.
> >>> I am open to any solution to get the cable properties dynamically.
> >>> Do you find a better but generic mechanism for this?
> >>>
> >>> I am trying to extend  extcon just because I couldn’t find any other
> >>> subsystem which gives cable notifications. IMHO, it's good if we can
> >>> avoid consumer and provider driver level dependencies just by
> >>> extending extcon. This will ensure that the same driver will work on
> >>> any
> >> platform as long as it's having the dependency only on extcon.
> >>> We shouldn't put any driver level dependency between extcon
> consumer
> >> and provider.
> >>> When we do like that, the extcon consumer is expecting the similar
> >>> implementation for the provider on all platforms. This may not be
> >>> possible
> >> Is there anything wrong in assuming similar implementation for all
> >> the providers?I think the providers know what it can provide and this
> >> may vary quite a lot.Or can we make a generic provider driver which
> >> will encompass all the randomness in the various provider
> >> drivers?This generic driver will get all the properties and since it
> >> will be generice anyone can use it to know what properties to expect.This
> will keep the extcon design intact.
> >
> > Maintainer??
> 
> I agreed about opinion of anish singh. The extcon provider driver provide
> generic
> 
> ----
> struct  extcon_cablel_props {
>      unsigned int cable_state;
>      unsigned int data;
> }
> ----
> You suggested upper structure and said it is only flexible to represent
> additional state, But, it is non-standard. What store real data on "unsigned int
> data"? It isn't determined and flexible. That is extcon consumer driver should
> already know type of real data or value of real data. The extcon consumer
> driver has strong dependency on extcon provider driver. In this case, if
> extcon provider driver can change data value of "unsigned int data", extcon
> consumer provider have to be modified according to extcon provider driver.
> I think it isn't correct apporach. So, I proposed that we should define
> properties for all cables.

I couldn’t find properties common for all type of cables. Alternate method I can think of is
a new driver "extcon-charger.c".  This driver will register with extcon subsystem.

The consumer and provider can use the APIs and properties exposed by this driver.  This
way we can ensure that extcon design is intact and the additional charger cable state and
properties can be handled by this driver. Does that make sense?

> 
> >>
> >>> and does not seems to  be a scalable solution. IMHO, the extcon
> >>> should provide a mechanism to retrieve the cable properties.
> >>> Consumer drivers can use this API to get the cable properties
> >>> without knowing the provider driver implementation. This will  make
> >>> the extcon drivers more
> >> scalable and reusable across multiple platforms.
> >>>
> >>>>>
> >>>>> Hope above structure would be enough to represent the common
> cable
> >>>>> state and it's data. If a cable has more than two states, then
> >>>>> extcon_update_state can be used to notify the consumer 1)Provider
> >>>>> can just toggle the "state" argument to notify the consumer that
> >>>>> cable state is changed OR
> >>>>> 2) Add one more argument  like  extcon_update_state(struct
> >>>>> extcon_dev *edev, u32 mask, u32 state1, u32 sate2)
> >>>> This will cause other drivers to change such as arizona.
> >>>>> If the state2 is set, then consumers can use
> >>>>> get_cable_properties() to query the cable properties. State2 need
> >>>>> to be used only if the cable need to represent more than two state
> >>>>>
> >>>>>>
> >>>>>> Third,
> >>>>>> If we finish to decide the properties for all cables, I'd like to
> >>>>>> see a example
> >>>> Why do we think that state and property is the only thing which the
> >>>> consumer want to know?I am sure there would be some more
> properties
> >>>> which would be of some interest to consumers and there is quite a
> >>>> possibility that in future we might get a patch for that also.So
> >>>> instead of that limiting it to just state is a good idea.
> >>>>>> code.
> >>>>>
> >>>>> Agreed. If we  agree on the above structure, I can modify the
> >>>>> charging subsystem patch to use the same structure.
> >>>>> (https://lkml.org/lkml/2012/10/18/219). This would give a
> >>>>> reference for the
> >>>> new feature.
> >>>>>
> >>>>>>
> >>>>>> You explained following changed state of USB according to Host
> >>>>>> state on other patch.
> >>>>>> ---------------------------
> >>>>>> For USB2.0
> >>>>>> 1) CONNECT (100mA)->UPDATE(500mA)->DISCONNECT(0mA)
> >>>>>> 2) CONNECT (100mA)->UPDATE(500mA)->HOST
> >>>> SUSPEND(2.5mA/500mA)-
> >>>>>>> DISCONNECT(0mA)
> >>>>>> 3) CONNECT (100mA)->UPDATE(500mA)->HOST
> >>>> SUSPEND(2.5mA/500mA)-
> >>>>>>> HOST RESUME(500mA)->DISCONNECT(0mA)
> >>>>>>
> >>>>>> For USB 3.0
> >>>>>> 4) CONNECT (150mA)->UPDATE(900mA)->DISCONNECT(0mA)
> >>>>>> 5) CONNECT (150mA)->UPDATE(900mA)-> HOST
> >>>> SUSPEND(2.5mA/900mA)-
> >>>>>>> DISCONNECT(0mA)
> >>>>>> 6) CONNECT (100mA)->UPDATE(900mA)->HOST
> >>>> SUSPEND(2.5mA/900mA)-
> >>>>>>> HOST RESUME(900mA)->DISCONNECT(0mA)
> >>>>>> ---------------------------
> >>>>>>
> >>>>>> I have a question. Can the provider device driver(e.g.,
> >>>>>> extcon-max77693.c/
> >>>>>> extcon-max8997.c) detect the changed state of host? I'd like to
> >>>>>> see the example device driver that the provider device driver
> >>>>>> detect changed state of host.
> >>>>>> Could you provide example device driver?
> >>>>>
> >>>>> Good question. The OTG drivers are capable of identifying the
> >>>>> SUSPEND
> >>>> event.
> >>>>> System cannot setup SDP (USB host) charging with maximum charging
> >>>>> current - 500mA (USB2.0/ 900mA(USB 3)) without enumerating the
> USB.
> >>>>> The USB enumeration can be done only with a USB/OTG driver. IMHO
> >>>>> the above extcon drivers (extcon-max77693.c/ extcon-max8997.c) are
> >>>>> not capable of doing the USB enumeration and identifying the
> >>>>> charge current. They can just identify the charger type -
> >> SDP/DCP/CDP/ACA/AC.
> >>>>> The intelligence for USB enumeration should be inside USB/OTG
> driver.
> 

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Re: [PATCH] extcon : callback function to read cable property

[Chanwoo Choi]

On 11/20/2012 11:42 AM, Tc, Jenny wrote:
>>>>>>>> I think that the role of extcon subsystem notify changed
>>>>>>>> state(attached/detached) of cable to notifiee, but if you want to
>>>>>>>> add property feature of cable, you should solve ambiguous issues.
>>>>>>>>
>>>>>>>> First,
>>>>>>>> This patch only support the properties of charger cable but,
>>>>>>>> never support property of other cable. The following structure
>>>>>>>> depend on only charger cable. We can check it the following
>> structure:
>>>>>>>>   struct extcon_chrg_cbl_props {
>>>>>>>>           enum extcon_chrgr_cbl_stat cable_state;
>>>>>>>>           unsigned long mA;
>>>>>>>>   };
>>>>>>>>
>>>>>>>> I think that the patch have to support all of cables for property
>>>> feature.
>>>>>>>
>>>>>>> My suggestion is to have a structure like this
>>>>>>>
>>>>>>> struct  extcon_cablel_props {
>>>>>>>     unsigned int cable_state;
>>>>>>>             unsigned int data;
>>>>>> Why can't it be float/long/double??
>>>>>>> }
>>>>>>> Not all cables will have more than two states. If any cable has
>>>>>>> more than two states, the above structure makes it flexible to
>>>>>>> represent additional state and the data associated
>>>>>>>
>>>>>>>>
>>>>>>>> Second,
>>>>>>>> Certainly, you should define common properties of all cables and
>>>>>>>> specific properties of each cable. The properties of charger
>>>>>>>> cable should never be defined only.
>>>>>> IMHO the extcon doesn't know anything about the cable except the
>>>>>> state which is currently it is in and which also is set by the
>>>>>> provider.I am unable to understand why should extcon provide more
>>>>>> than what it knows?It should just limit itself to broadcasting the
>>>>>> cable state and exploiting it for any other information would only
>>>>>> lead to
>>>> more un-necessary code.
>>>>>> It should be same as IIO subsystem where the consumer and provider
>>>>>> knows before hand what information they are going to share and with
>>>>>> what precision and IIO core is just a way to do that.It doesn't
>>>>>> know anything beyond what is given by the provider.
>>>>>> Same is the case with driver core where individual driver sets it's
>>>>>> own private data and the driver core just gives that private data
>>>>>> back to the driver as and when it needs but parsing the private
>>>>>> data in the right way is up to the individual driver.
>>>>>>
>>>>>> I fail to understand why is not the case here.
>>>>>
>>>>> The requirement is different from the IIO case. I am trying to
>>>>> extend the Power Supply class to support charging in a generic way
>>>> (https://lkml.org/lkml/2012/10/18/219).
>>>>> The extcon consumer in this case is not a device driver. It's part
>>>>> of power
>>>> supply class driver itself.
>>>>> I am open to any solution to get the cable properties dynamically.
>>>>> Do you find a better but generic mechanism for this?
>>>>>
>>>>> I am trying to extend  extcon just because I couldn’t find any other
>>>>> subsystem which gives cable notifications. IMHO, it's good if we can
>>>>> avoid consumer and provider driver level dependencies just by
>>>>> extending extcon. This will ensure that the same driver will work on
>>>>> any
>>>> platform as long as it's having the dependency only on extcon.
>>>>> We shouldn't put any driver level dependency between extcon
>> consumer
>>>> and provider.
>>>>> When we do like that, the extcon consumer is expecting the similar
>>>>> implementation for the provider on all platforms. This may not be
>>>>> possible
>>>> Is there anything wrong in assuming similar implementation for all
>>>> the providers?I think the providers know what it can provide and this
>>>> may vary quite a lot.Or can we make a generic provider driver which
>>>> will encompass all the randomness in the various provider
>>>> drivers?This generic driver will get all the properties and since it
>>>> will be generice anyone can use it to know what properties to expect.This
>> will keep the extcon design intact.
>>>
>>> Maintainer??
>>
>> I agreed about opinion of anish singh. The extcon provider driver provide
>> generic
>>
>> ----
>> struct  extcon_cablel_props {
>>      unsigned int cable_state;
>>      unsigned int data;
>> }
>> ----
>> You suggested upper structure and said it is only flexible to represent
>> additional state, But, it is non-standard. What store real data on "unsigned int
>> data"? It isn't determined and flexible. That is extcon consumer driver should
>> already know type of real data or value of real data. The extcon consumer
>> driver has strong dependency on extcon provider driver. In this case, if
>> extcon provider driver can change data value of "unsigned int data", extcon
>> consumer provider have to be modified according to extcon provider driver.
>> I think it isn't correct apporach. So, I proposed that we should define
>> properties for all cables.
> 
> I couldn’t find properties common for all type of cables. Alternate method I can think of is
> a new driver "extcon-charger.c".  This driver will register with extcon subsystem.
> 
> The consumer and provider can use the APIs and properties exposed by this driver.  This
> way we can ensure that extcon design is intact and the additional charger cable state and
> properties can be handled by this driver. Does that make sense?

I don't agree about 'extcon-charger.c' because the 'extcon-class.c' driver support already charger
cable.
Also it is duplicate feature between 'extcon-class.c' and 'extcon-charger.c'.

Also,
The obvious difference between the state of external cable and the state of host system is existence.
I think that extcon cable state isn't changed when state of host system
move from normal state to suspend state or opposite case. If consumer driver
hope to know new state of host system, power_supply charging framework
communicate with other driver or framework that provide API for checking state
of host system.

I suggest a approach that some framework related OTG/USB need to implement
something like below notifier block, this notifier block inform changed state
of host system of some driver/framework that need state of host system.

/*
  * Host system notifier
  */
#define HOST_SYSTEM_NORMAL		0x1
#define HOST_SYSTEM_SUSPEND	0x2

extern int register_host_system_notifier(struct notifier_block *nb);
extern void unregister_host_system_notifier(struct notifier_block *nb);
int host_system_notify(..)

For example,
Firstly, the power_supply charging framework check state of charger cable whether
attached or detached cable. Second, when power_supply charging framework
receive the changed state of host system from 'Host system notifier',
change charging current of charger cable.

> 
>>
>>>>
>>>>> and does not seems to  be a scalable solution. IMHO, the extcon
>>>>> should provide a mechanism to retrieve the cable properties.
>>>>> Consumer drivers can use this API to get the cable properties
>>>>> without knowing the provider driver implementation. This will  make
>>>>> the extcon drivers more
>>>> scalable and reusable across multiple platforms.
>>>>>
>>>>>>>
>>>>>>> Hope above structure would be enough to represent the common
>> cable
>>>>>>> state and it's data. If a cable has more than two states, then
>>>>>>> extcon_update_state can be used to notify the consumer 1)Provider
>>>>>>> can just toggle the "state" argument to notify the consumer that
>>>>>>> cable state is changed OR
>>>>>>> 2) Add one more argument  like  extcon_update_state(struct
>>>>>>> extcon_dev *edev, u32 mask, u32 state1, u32 sate2)
>>>>>> This will cause other drivers to change such as arizona.
>>>>>>> If the state2 is set, then consumers can use
>>>>>>> get_cable_properties() to query the cable properties. State2 need
>>>>>>> to be used only if the cable need to represent more than two state
>>>>>>>
>>>>>>>>
>>>>>>>> Third,
>>>>>>>> If we finish to decide the properties for all cables, I'd like to
>>>>>>>> see a example
>>>>>> Why do we think that state and property is the only thing which the
>>>>>> consumer want to know?I am sure there would be some more
>> properties
>>>>>> which would be of some interest to consumers and there is quite a
>>>>>> possibility that in future we might get a patch for that also.So
>>>>>> instead of that limiting it to just state is a good idea.
>>>>>>>> code.
>>>>>>>
>>>>>>> Agreed. If we  agree on the above structure, I can modify the
>>>>>>> charging subsystem patch to use the same structure.
>>>>>>> (https://lkml.org/lkml/2012/10/18/219). This would give a
>>>>>>> reference for the
>>>>>> new feature.
>>>>>>>
>>>>>>>>
>>>>>>>> You explained following changed state of USB according to Host
>>>>>>>> state on other patch.
>>>>>>>> ---------------------------
>>>>>>>> For USB2.0
>>>>>>>> 1) CONNECT (100mA)->UPDATE(500mA)->DISCONNECT(0mA)
>>>>>>>> 2) CONNECT (100mA)->UPDATE(500mA)->HOST
>>>>>> SUSPEND(2.5mA/500mA)-
>>>>>>>>> DISCONNECT(0mA)
>>>>>>>> 3) CONNECT (100mA)->UPDATE(500mA)->HOST
>>>>>> SUSPEND(2.5mA/500mA)-
>>>>>>>>> HOST RESUME(500mA)->DISCONNECT(0mA)
>>>>>>>>
>>>>>>>> For USB 3.0
>>>>>>>> 4) CONNECT (150mA)->UPDATE(900mA)->DISCONNECT(0mA)
>>>>>>>> 5) CONNECT (150mA)->UPDATE(900mA)-> HOST
>>>>>> SUSPEND(2.5mA/900mA)-
>>>>>>>>> DISCONNECT(0mA)
>>>>>>>> 6) CONNECT (100mA)->UPDATE(900mA)->HOST
>>>>>> SUSPEND(2.5mA/900mA)-
>>>>>>>>> HOST RESUME(900mA)->DISCONNECT(0mA)
>>>>>>>> ---------------------------
>>>>>>>>
>>>>>>>> I have a question. Can the provider device driver(e.g.,
>>>>>>>> extcon-max77693.c/
>>>>>>>> extcon-max8997.c) detect the changed state of host? I'd like to
>>>>>>>> see the example device driver that the provider device driver
>>>>>>>> detect changed state of host.
>>>>>>>> Could you provide example device driver?
>>>>>>>
>>>>>>> Good question. The OTG drivers are capable of identifying the
>>>>>>> SUSPEND
>>>>>> event.
>>>>>>> System cannot setup SDP (USB host) charging with maximum charging
>>>>>>> current - 500mA (USB2.0/ 900mA(USB 3)) without enumerating the
>> USB.
>>>>>>> The USB enumeration can be done only with a USB/OTG driver. IMHO
>>>>>>> the above extcon drivers (extcon-max77693.c/ extcon-max8997.c) are
>>>>>>> not capable of doing the USB enumeration and identifying the
>>>>>>> charge current. They can just identify the charger type -
>>>> SDP/DCP/CDP/ACA/AC.
>>>>>>> The intelligence for USB enumeration should be inside USB/OTG
>> driver.
>>
> 

RE: [PATCH] extcon : callback function to read cable property

[Tc, Jenny]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset="utf-8", Size: 13410 bytes --]

> >>>>>>>> I think that the role of extcon subsystem notify changed
> >>>>>>>> state(attached/detached) of cable to notifiee, but if you want
> >>>>>>>> to add property feature of cable, you should solve ambiguous
> issues.
> >>>>>>>>
> >>>>>>>> First,
> >>>>>>>> This patch only support the properties of charger cable but,
> >>>>>>>> never support property of other cable. The following structure
> >>>>>>>> depend on only charger cable. We can check it the following
> >> structure:
> >>>>>>>>   struct extcon_chrg_cbl_props {
> >>>>>>>>           enum extcon_chrgr_cbl_stat cable_state;
> >>>>>>>>           unsigned long mA;
> >>>>>>>>   };
> >>>>>>>>
> >>>>>>>> I think that the patch have to support all of cables for
> >>>>>>>> property
> >>>> feature.
> >>>>>>>
> >>>>>>> My suggestion is to have a structure like this
> >>>>>>>
> >>>>>>> struct  extcon_cablel_props {
> >>>>>>>     unsigned int cable_state;
> >>>>>>>             unsigned int data;
> >>>>>> Why can't it be float/long/double??
> >>>>>>> }
> >>>>>>> Not all cables will have more than two states. If any cable has
> >>>>>>> more than two states, the above structure makes it flexible to
> >>>>>>> represent additional state and the data associated
> >>>>>>>
> >>>>>>>>
> >>>>>>>> Second,
> >>>>>>>> Certainly, you should define common properties of all cables
> >>>>>>>> and specific properties of each cable. The properties of
> >>>>>>>> charger cable should never be defined only.
> >>>>>> IMHO the extcon doesn't know anything about the cable except the
> >>>>>> state which is currently it is in and which also is set by the
> >>>>>> provider.I am unable to understand why should extcon provide
> more
> >>>>>> than what it knows?It should just limit itself to broadcasting
> >>>>>> the cable state and exploiting it for any other information would
> >>>>>> only lead to
> >>>> more un-necessary code.
> >>>>>> It should be same as IIO subsystem where the consumer and
> >>>>>> provider knows before hand what information they are going to
> >>>>>> share and with what precision and IIO core is just a way to do
> >>>>>> that.It doesn't know anything beyond what is given by the provider.
> >>>>>> Same is the case with driver core where individual driver sets
> >>>>>> it's own private data and the driver core just gives that private
> >>>>>> data back to the driver as and when it needs but parsing the
> >>>>>> private data in the right way is up to the individual driver.
> >>>>>>
> >>>>>> I fail to understand why is not the case here.
> >>>>>
> >>>>> The requirement is different from the IIO case. I am trying to
> >>>>> extend the Power Supply class to support charging in a generic way
> >>>> (https://lkml.org/lkml/2012/10/18/219).
> >>>>> The extcon consumer in this case is not a device driver. It's part
> >>>>> of power
> >>>> supply class driver itself.
> >>>>> I am open to any solution to get the cable properties dynamically.
> >>>>> Do you find a better but generic mechanism for this?
> >>>>>
> >>>>> I am trying to extend  extcon just because I couldn’t find any
> >>>>> other subsystem which gives cable notifications. IMHO, it's good
> >>>>> if we can avoid consumer and provider driver level dependencies
> >>>>> just by extending extcon. This will ensure that the same driver
> >>>>> will work on any
> >>>> platform as long as it's having the dependency only on extcon.
> >>>>> We shouldn't put any driver level dependency between extcon
> >> consumer
> >>>> and provider.
> >>>>> When we do like that, the extcon consumer is expecting the similar
> >>>>> implementation for the provider on all platforms. This may not be
> >>>>> possible
> >>>> Is there anything wrong in assuming similar implementation for all
> >>>> the providers?I think the providers know what it can provide and
> >>>> this may vary quite a lot.Or can we make a generic provider driver
> >>>> which will encompass all the randomness in the various provider
> >>>> drivers?This generic driver will get all the properties and since
> >>>> it will be generice anyone can use it to know what properties to
> >>>> expect.This
> >> will keep the extcon design intact.
> >>>
> >>> Maintainer??
> >>
> >> I agreed about opinion of anish singh. The extcon provider driver
> >> provide generic
> >>
> >> ----
> >> struct  extcon_cablel_props {
> >>      unsigned int cable_state;
> >>      unsigned int data;
> >> }
> >> ----
> >> You suggested upper structure and said it is only flexible to
> >> represent additional state, But, it is non-standard. What store real
> >> data on "unsigned int data"? It isn't determined and flexible. That
> >> is extcon consumer driver should already know type of real data or
> >> value of real data. The extcon consumer driver has strong dependency
> >> on extcon provider driver. In this case, if extcon provider driver
> >> can change data value of "unsigned int data", extcon consumer provider
> have to be modified according to extcon provider driver.
> >> I think it isn't correct apporach. So, I proposed that we should
> >> define properties for all cables.
> >
> > I couldn’t find properties common for all type of cables. Alternate
> > method I can think of is a new driver "extcon-charger.c".  This driver will
> register with extcon subsystem.
> >
> > The consumer and provider can use the APIs and properties exposed by
> > this driver.  This way we can ensure that extcon design is intact and
> > the additional charger cable state and properties can be handled by this
> driver. Does that make sense?
> 
> I don't agree about 'extcon-charger.c' because the 'extcon-class.c' driver
> support already charger cable.
> Also it is duplicate feature between 'extcon-class.c' and 'extcon-charger.c'.
> 
> Also,
> The obvious difference between the state of external cable and the state of
> host system is existence.
> I think that extcon cable state isn't changed when state of host system move
> from normal state to suspend state or opposite case. If consumer driver
> hope to know new state of host system, power_supply charging framework
> communicate with other driver or framework that provide API for checking
> state of host system.
> 
> I suggest a approach that some framework related OTG/USB need to
> implement something like below notifier block, this notifier block inform
> changed state of host system of some driver/framework that need state of
> host system.
> 
> /*
>   * Host system notifier
>   */
> #define HOST_SYSTEM_NORMAL		0x1
> #define HOST_SYSTEM_SUSPEND	0x2
> 
> extern int register_host_system_notifier(struct notifier_block *nb); extern
> void unregister_host_system_notifier(struct notifier_block *nb); int
> host_system_notify(..)
> 
> For example,
> Firstly, the power_supply charging framework check state of charger cable
> whether attached or detached cable. Second, when power_supply charging
> framework receive the changed state of host system from 'Host system
> notifier', change charging current of charger cable.

Not just SUSPEND, but we need to handle RESUME , UPDATE etc.  Also this doesn’t help us to
define a standard interface for the charger cable state/properties. IMHO it's not right
to provide different interfaces for different cables. This doesn't help us to standardize
the charger cable interface.

This thread has been running for a quite long time. Unfortunately we couldn't make an
agreement on the final solution. I would like to recap the overall requirement and
would like to propose alternate solutions. The requirements is  to
"Provide a generic interface for charger cable states and charger cable properties"

Even though extcon subsystem handles charger cable states, it's not enough to handle
all kind of charger cable states. It can handle just 2 states CONNECT/DISCONNECT.
But there are scenarios where we need to handle more than 2 states
(eg. USB SUSPEND/RESUME/UPDATE etc). Also extcon doesn't have any mechanism to
read cable properties in a generic way.  Extcon charger-cable consumer driver
implementations (eg charger-manager), defines charger cable properties statically (current in mA)
inside the consumer driver. This is not enough, since the charger cable properties may change dynamically

In existing form extcon cannot support different charger cable states and their 
properties in a generic way. Also we couldn't find a final solution on how to modify the
extcon to support these requirements. From the whole discussion what I conclude is
 * extcon is not designed to support cable properties
 * extcon is not designed to support any cable state other than CONNECT/DISCONNECT

(Feel free to correct me if my conclusion is wrong)


Considering these facts and the above discussion, what I feel is extcon subsystem cannot provide generic
interface to handle multiple charger cable states and their properties

Based on this, I would like to propose a generic interface for the charger cable notification which
can handle multiple cable states and can provide charger cable properties in a generic manner.
Since the charger cables are related to power supply subsystem, my suggestion is to have a notifier
chain inside the power_supply subsystem  and have APIs to query the charger cable properties.
This will help to standardize the charger cable handling.

Both extcon and power_supply maintainers are CCed in this thread. Please help me to identify a solution.


> 
> >
> >>
> >>>>
> >>>>> and does not seems to  be a scalable solution. IMHO, the extcon
> >>>>> should provide a mechanism to retrieve the cable properties.
> >>>>> Consumer drivers can use this API to get the cable properties
> >>>>> without knowing the provider driver implementation. This will
> >>>>> make the extcon drivers more
> >>>> scalable and reusable across multiple platforms.
> >>>>>
> >>>>>>>
> >>>>>>> Hope above structure would be enough to represent the common
> >> cable
> >>>>>>> state and it's data. If a cable has more than two states, then
> >>>>>>> extcon_update_state can be used to notify the consumer
> >>>>>>> 1)Provider can just toggle the "state" argument to notify the
> >>>>>>> consumer that cable state is changed OR
> >>>>>>> 2) Add one more argument  like  extcon_update_state(struct
> >>>>>>> extcon_dev *edev, u32 mask, u32 state1, u32 sate2)
> >>>>>> This will cause other drivers to change such as arizona.
> >>>>>>> If the state2 is set, then consumers can use
> >>>>>>> get_cable_properties() to query the cable properties. State2
> >>>>>>> need to be used only if the cable need to represent more than
> >>>>>>> two state
> >>>>>>>
> >>>>>>>>
> >>>>>>>> Third,
> >>>>>>>> If we finish to decide the properties for all cables, I'd like
> >>>>>>>> to see a example
> >>>>>> Why do we think that state and property is the only thing which
> >>>>>> the consumer want to know?I am sure there would be some more
> >> properties
> >>>>>> which would be of some interest to consumers and there is quite a
> >>>>>> possibility that in future we might get a patch for that also.So
> >>>>>> instead of that limiting it to just state is a good idea.
> >>>>>>>> code.
> >>>>>>>
> >>>>>>> Agreed. If we  agree on the above structure, I can modify the
> >>>>>>> charging subsystem patch to use the same structure.
> >>>>>>> (https://lkml.org/lkml/2012/10/18/219). This would give a
> >>>>>>> reference for the
> >>>>>> new feature.
> >>>>>>>
> >>>>>>>>
> >>>>>>>> You explained following changed state of USB according to Host
> >>>>>>>> state on other patch.
> >>>>>>>> ---------------------------
> >>>>>>>> For USB2.0
> >>>>>>>> 1) CONNECT (100mA)->UPDATE(500mA)->DISCONNECT(0mA)
> >>>>>>>> 2) CONNECT (100mA)->UPDATE(500mA)->HOST
> >>>>>> SUSPEND(2.5mA/500mA)-
> >>>>>>>>> DISCONNECT(0mA)
> >>>>>>>> 3) CONNECT (100mA)->UPDATE(500mA)->HOST
> >>>>>> SUSPEND(2.5mA/500mA)-
> >>>>>>>>> HOST RESUME(500mA)->DISCONNECT(0mA)
> >>>>>>>>
> >>>>>>>> For USB 3.0
> >>>>>>>> 4) CONNECT (150mA)->UPDATE(900mA)->DISCONNECT(0mA)
> >>>>>>>> 5) CONNECT (150mA)->UPDATE(900mA)-> HOST
> >>>>>> SUSPEND(2.5mA/900mA)-
> >>>>>>>>> DISCONNECT(0mA)
> >>>>>>>> 6) CONNECT (100mA)->UPDATE(900mA)->HOST
> >>>>>> SUSPEND(2.5mA/900mA)-
> >>>>>>>>> HOST RESUME(900mA)->DISCONNECT(0mA)
> >>>>>>>> ---------------------------
> >>>>>>>>
> >>>>>>>> I have a question. Can the provider device driver(e.g.,
> >>>>>>>> extcon-max77693.c/
> >>>>>>>> extcon-max8997.c) detect the changed state of host? I'd like to
> >>>>>>>> see the example device driver that the provider device driver
> >>>>>>>> detect changed state of host.
> >>>>>>>> Could you provide example device driver?
> >>>>>>>
> >>>>>>> Good question. The OTG drivers are capable of identifying the
> >>>>>>> SUSPEND
> >>>>>> event.
> >>>>>>> System cannot setup SDP (USB host) charging with maximum
> >>>>>>> charging current - 500mA (USB2.0/ 900mA(USB 3)) without
> >>>>>>> enumerating the
> >> USB.
> >>>>>>> The USB enumeration can be done only with a USB/OTG driver.
> IMHO
> >>>>>>> the above extcon drivers (extcon-max77693.c/ extcon-max8997.c)
> >>>>>>> are not capable of doing the USB enumeration and identifying the
> >>>>>>> charge current. They can just identify the charger type -
> >>>> SDP/DCP/CDP/ACA/AC.
> >>>>>>> The intelligence for USB enumeration should be inside USB/OTG
> >> driver.
> >>
> >
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Re: [PATCH] extcon : callback function to read cable property

[Anton Vorontsov]

On Tue, Nov 20, 2012 at 09:14:41AM +0000, Tc, Jenny wrote:
[...]
> > For example,
> > Firstly, the power_supply charging framework check state of charger cable
> > whether attached or detached cable. Second, when power_supply charging
> > framework receive the changed state of host system from 'Host system
> > notifier', change charging current of charger cable.
> 
> Not just SUSPEND, but we need to handle RESUME , UPDATE etc.  Also this doesn’t help us to
> define a standard interface for the charger cable state/properties. IMHO it's not right
> to provide different interfaces for different cables. This doesn't help us to standardize
> the charger cable interface.
> 
> This thread has been running for a quite long time. Unfortunately we couldn't make an
> agreement on the final solution. I would like to recap the overall requirement and
> would like to propose alternate solutions. The requirements is  to
> "Provide a generic interface for charger cable states and charger cable properties"
> 
> Even though extcon subsystem handles charger cable states, it's not enough to handle
> all kind of charger cable states. It can handle just 2 states CONNECT/DISCONNECT.
> But there are scenarios where we need to handle more than 2 states
> (eg. USB SUSPEND/RESUME/UPDATE etc). Also extcon doesn't have any mechanism to
> read cable properties in a generic way.  Extcon charger-cable consumer driver
> implementations (eg charger-manager), defines charger cable properties statically (current in mA)
> inside the consumer driver. This is not enough, since the charger cable properties may change dynamically
> 
> In existing form extcon cannot support different charger cable states and their 
> properties in a generic way. Also we couldn't find a final solution on how to modify the
> extcon to support these requirements. From the whole discussion what I conclude is
>  * extcon is not designed to support cable properties

The idea of using union seemed good to me, what happened to it?

I mean, MyungJoo Ham wrote:

| We may have:
|        enum extcon_cable_type {
|                EXTCON_CT_REGULATOR,
|                EXTCON_CT_PSY,
|                EXTCON_CT_CHARGER_CB,
|                ...
|        };
| and have the following included at struct extcon_cable:
|        union {
|                struct regulator *reg;
|                struct power_supply *psy;
|                struct charger_cable *charger_cb;
|                ...
|        } cable data;
|        enum extcon_cable_type cable_type;

This sounds good to me...

>  * extcon is not designed to support any cable state other than CONNECT/DISCONNECT

Dunno for this one. Can we get these additional states via "properties" as
described above?

Thanks,
Anton.

Re: [PATCH] extcon : callback function to read cable property

[anish singh]

On Tue, Nov 20, 2012 at 1:24 AM, Anton Vorontsov <cbouatmailru@gmail.com> wrote:
> On Tue, Nov 20, 2012 at 09:14:41AM +0000, Tc, Jenny wrote:
> [...]
>> > For example,
>> > Firstly, the power_supply charging framework check state of charger cable
>> > whether attached or detached cable. Second, when power_supply charging
>> > framework receive the changed state of host system from 'Host system
>> > notifier', change charging current of charger cable.
>>
>> Not just SUSPEND, but we need to handle RESUME , UPDATE etc.  Also this doesn’t help us to
>> define a standard interface for the charger cable state/properties. IMHO it's not right
>> to provide different interfaces for different cables. This doesn't help us to standardize
>> the charger cable interface.
>>
>> This thread has been running for a quite long time. Unfortunately we couldn't make an
>> agreement on the final solution. I would like to recap the overall requirement and
>> would like to propose alternate solutions. The requirements is  to
>> "Provide a generic interface for charger cable states and charger cable properties"
>>
>> Even though extcon subsystem handles charger cable states, it's not enough to handle
>> all kind of charger cable states. It can handle just 2 states CONNECT/DISCONNECT.
>> But there are scenarios where we need to handle more than 2 states
>> (eg. USB SUSPEND/RESUME/UPDATE etc). Also extcon doesn't have any mechanism to
>> read cable properties in a generic way.  Extcon charger-cable consumer driver
>> implementations (eg charger-manager), defines charger cable properties statically (current in mA)
>> inside the consumer driver. This is not enough, since the charger cable properties may change dynamically
>>
>> In existing form extcon cannot support different charger cable states and their
>> properties in a generic way. Also we couldn't find a final solution on how to modify the
>> extcon to support these requirements. From the whole discussion what I conclude is
>>  * extcon is not designed to support cable properties
>
> The idea of using union seemed good to me, what happened to it?
>
> I mean, MyungJoo Ham wrote:
>
> | We may have:
> |        enum extcon_cable_type {
> |                EXTCON_CT_REGULATOR,
> |                EXTCON_CT_PSY,
> |                EXTCON_CT_CHARGER_CB,
> |                ...
> |        };
> | and have the following included at struct extcon_cable:
> |        union {
> |                struct regulator *reg;
> |                struct power_supply *psy;
> |                struct charger_cable *charger_cb;
> |                ...
> |        } cable data;
> |        enum extcon_cable_type cable_type;
>
> This sounds good to me...
+1 for this idea.
>
>>  * extcon is not designed to support any cable state other than CONNECT/DISCONNECT
>
> Dunno for this one. Can we get these additional states via "properties" as
> described above?
>
> Thanks,
> Anton.

RE: [PATCH] extcon : callback function to read cable property

[Tc, Jenny]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset="utf-8", Size: 4445 bytes --]

> > > For example,
> > > Firstly, the power_supply charging framework check state of charger
> > > cable whether attached or detached cable. Second, when power_supply
> > > charging framework receive the changed state of host system from
> > > 'Host system notifier', change charging current of charger cable.
> >
> > Not just SUSPEND, but we need to handle RESUME , UPDATE etc.  Also
> > this doesn’t help us to define a standard interface for the charger
> > cable state/properties. IMHO it's not right to provide different
> > interfaces for different cables. This doesn't help us to standardize the
> charger cable interface.
> >
> > This thread has been running for a quite long time. Unfortunately we
> > couldn't make an agreement on the final solution. I would like to
> > recap the overall requirement and would like to propose alternate
> > solutions. The requirements is  to "Provide a generic interface for charger
> cable states and charger cable properties"
> >
> > Even though extcon subsystem handles charger cable states, it's not
> > enough to handle all kind of charger cable states. It can handle just 2 states
> CONNECT/DISCONNECT.
> > But there are scenarios where we need to handle more than 2 states
> > (eg. USB SUSPEND/RESUME/UPDATE etc). Also extcon doesn't have any
> > mechanism to read cable properties in a generic way.  Extcon
> > charger-cable consumer driver implementations (eg charger-manager),
> > defines charger cable properties statically (current in mA) inside the
> > consumer driver. This is not enough, since the charger cable
> > properties may change dynamically
> >
> > In existing form extcon cannot support different charger cable states
> > and their properties in a generic way. Also we couldn't find a final
> > solution on how to modify the extcon to support these requirements.
> > From the whole discussion what I conclude is
> >  * extcon is not designed to support cable properties
> 
> The idea of using union seemed good to me, what happened to it?
> 
> I mean, MyungJoo Ham wrote:
> 
> | We may have:
> |        enum extcon_cable_type {
> |                EXTCON_CT_REGULATOR,
> |                EXTCON_CT_PSY,
> |                EXTCON_CT_CHARGER_CB,
> |                ...
> |        };
> | and have the following included at struct extcon_cable:
> |        union {
> |                struct regulator *reg;
> |                struct power_supply *psy;
> |                struct charger_cable *charger_cb;
> |                ...
> |        } cable data;
> |        enum extcon_cable_type cable_type;
> 
> This sounds good to me...

If I am right, this logic will help the consumer to know who will provide the properties and states.
But currently none of these subsystems are capable of giving the charger cable properties
because the information will be available only to the "provider driver". The provider driver
need not to be in any of these subsystem. For example if the OTG driver need to notify the
cable state (CONNECT/DISCONNECT/SUSPEND/RESUME..) and the properties (current in mA),
it doesn't make sense to register the OTG driver with any of these subsystems. 
But still it make sense to register with extcon since it can give the cable state information. 
I think this is applicable for all cable provider drivers.

If we are fine with union, then can we have the cable properties defined as unions?

struct charger_cable_props {
	unsigned long state;
	int mA;
}
struct extcon_cable {
	.....
	union {
		struct charger_cable_props chrgr_props;
		.....
	} data;
	enum extcon_cable_name cable_name;
};

This way we are not restricting the cable properties just to the charger cable.
We can add other charger cable properties as we identify the properties for them.
We can use the cable_name variable to identify  which cable property to use.

> 
> >  * extcon is not designed to support any cable state other than
> > CONNECT/DISCONNEC
> 
> Dunno for this one. Can we get these additional states via "properties" as
> described above?
> 
> Thanks,
> Anton.
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Re: [PATCH] extcon : callback function to read cable property

[Anton Vorontsov]

On Tue, Nov 20, 2012 at 11:08:54AM +0000, Tc, Jenny wrote:
[...]
> > | We may have:
> > |        enum extcon_cable_type {
> > |                EXTCON_CT_REGULATOR,
> > |                EXTCON_CT_PSY,
> > |                EXTCON_CT_CHARGER_CB,
> > |                ...
> > |        };
> > | and have the following included at struct extcon_cable:
> > |        union {
> > |                struct regulator *reg;
> > |                struct power_supply *psy;
> > |                struct charger_cable *charger_cb;
> > |                ...
> > |        } cable data;
> > |        enum extcon_cable_type cable_type;
[...]
> struct charger_cable_props {
> 	unsigned long state;
> 	int mA;
> }
> struct extcon_cable {
> 	.....
> 	union {
> 		struct charger_cable_props chrgr_props;
> 		.....
> 	} data;
> 	enum extcon_cable_name cable_name;
> };
> 
> This way we are not restricting the cable properties just to the charger cable.
> We can add other charger cable properties as we identify the properties for them.

Well, to me, it seems that if we have cable *type*, then having properties
of the cable is the next logical step.

So, personally I see nothing wrong with it.

But you can look at this at the different angle: the type is just another
property of the cable. Would it be better to have power_supply-like API
for extcon? :)

if (extcon->get_prop(extcon, EXC_PROP_TYPE) == EXC_TYPE_CHARGER)) {
	int max_uA = extcon->get_prop(extcon, EXC_PROP_MAX_CURRENT;
	...
}

> We can use the cable_name variable to identify  which cable property to use.

This I didn't get, tho. Why would 'cable_name' tell us which property to
use?. The type of the cable defines a set of its properties -- this I can
understand.

Thanks,
Anton.