[PATCH] ARM: omap_hwmod: Add a new state to handle hwmods left enabled at init

[PATCH] ARM: omap_hwmod: Add a new state to handle hwmods left enabled at init

[Rajendra Nayak]

A hwmod with a 'HWMOD_INIT_NO_IDLE' flag set, is left in
enabled state by the hwmod framework post the initial setup.
Once a real user of the device (a driver) tries to enable it
at a later point, the hmwod framework throws a WARN() about
the device being already in enabled state.

Fix this by introducing a new state '_HWMOD_STATE_ENABLED_AT_INIT'
to identify such devices/hwmods, so nothing but just a state
change to '_HWMOD_STATE_ENABLED' can be done when the device/hwmod
is requested to be enabled (the first time) by its driver/user.

A good example of a such a device is an UART used as debug console.
The UART module needs to be kept enabled through the boot, until the
UART driver takes control of it, for debug prints to appear on
the console.

Signed-off-by: Rajendra Nayak <rnayak@ti.com>
---
 arch/arm/mach-omap2/omap_hwmod.c             |   16 ++++++++++++++--
 arch/arm/plat-omap/include/plat/omap_hwmod.h |    1 +
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/arch/arm/mach-omap2/omap_hwmod.c b/arch/arm/mach-omap2/omap_hwmod.c
index d7f4623..7d94cc3 100644
--- a/arch/arm/mach-omap2/omap_hwmod.c
+++ b/arch/arm/mach-omap2/omap_hwmod.c
@@ -1441,6 +1441,17 @@ static int _enable(struct omap_hwmod *oh)
 
 	pr_debug("omap_hwmod: %s: enabling\n", oh->name);
 
+	/*
+	 * hwmods' with HWMOD_INIT_NO_IDLE flag set, are left
+	 * in enabled state at init.
+	 * Now that someone is really trying to enable them,
+	 * just update the state.
+	 */
+	if (oh->_state == _HWMOD_STATE_ENABLED_AT_INIT) {
+		oh->_state = _HWMOD_STATE_ENABLED;
+		return 0;
+	}
+
 	if (oh->_state != _HWMOD_STATE_INITIALIZED &&
 	    oh->_state != _HWMOD_STATE_IDLE &&
 	    oh->_state != _HWMOD_STATE_DISABLED) {
@@ -1449,7 +1460,6 @@ static int _enable(struct omap_hwmod *oh)
 		return -EINVAL;
 	}
 
-
 	/*
 	 * If an IP contains only one HW reset line, then de-assert it in order
 	 * to allow the module state transition. Otherwise the PRCM will return
@@ -1744,8 +1754,10 @@ static int _setup(struct omap_hwmod *oh, void *data)
 	 * it should be set by the core code as a runtime flag during startup
 	 */
 	if ((oh->flags & HWMOD_INIT_NO_IDLE) &&
-	    (postsetup_state == _HWMOD_STATE_IDLE))
+	    (postsetup_state == _HWMOD_STATE_IDLE)) {
+		oh->_state = _HWMOD_STATE_ENABLED_AT_INIT;
 		postsetup_state = _HWMOD_STATE_ENABLED;
+	}
 
 	if (postsetup_state == _HWMOD_STATE_IDLE)
 		_idle(oh);
diff --git a/arch/arm/plat-omap/include/plat/omap_hwmod.h b/arch/arm/plat-omap/include/plat/omap_hwmod.h
index 1b81dfb..cd49d60 100644
--- a/arch/arm/plat-omap/include/plat/omap_hwmod.h
+++ b/arch/arm/plat-omap/include/plat/omap_hwmod.h
@@ -436,6 +436,7 @@ struct omap_hwmod_omap4_prcm {
 #define _HWMOD_STATE_ENABLED			4
 #define _HWMOD_STATE_IDLE			5
 #define _HWMOD_STATE_DISABLED			6
+#define _HWMOD_STATE_ENABLED_AT_INIT		7
 
 /**
  * struct omap_hwmod_class - the type of an IP block
-- 
1.7.1

Re: [PATCH] ARM: omap_hwmod: Add a new state to handle hwmods left enabled at init

[Cousson, Benoit]

+ Paul

On 11/17/2011 11:11 AM, Rajendra Nayak wrote:
> A hwmod with a 'HWMOD_INIT_NO_IDLE' flag set, is left in
> enabled state by the hwmod framework post the initial setup.
> Once a real user of the device (a driver) tries to enable it
> at a later point, the hmwod framework throws a WARN() about

typo: -------------------^

> the device being already in enabled state.
>
> Fix this by introducing a new state '_HWMOD_STATE_ENABLED_AT_INIT'
> to identify such devices/hwmods, so nothing but just a state
> change to '_HWMOD_STATE_ENABLED' can be done when the device/hwmod
> is requested to be enabled (the first time) by its driver/user.
>
> A good example of a such a device is an UART used as debug console.
> The UART module needs to be kept enabled through the boot, until the
> UART driver takes control of it, for debug prints to appear on
> the console.
>
> Signed-off-by: Rajendra Nayak<rnayak@ti.com>
> ---
>   arch/arm/mach-omap2/omap_hwmod.c             |   16 ++++++++++++++--
>   arch/arm/plat-omap/include/plat/omap_hwmod.h |    1 +
>   2 files changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm/mach-omap2/omap_hwmod.c b/arch/arm/mach-omap2/omap_hwmod.c
> index d7f4623..7d94cc3 100644
> --- a/arch/arm/mach-omap2/omap_hwmod.c
> +++ b/arch/arm/mach-omap2/omap_hwmod.c
> @@ -1441,6 +1441,17 @@ static int _enable(struct omap_hwmod *oh)
>
>   	pr_debug("omap_hwmod: %s: enabling\n", oh->name);
>
> +	/*
> +	 * hwmods' with HWMOD_INIT_NO_IDLE flag set, are left

Is the ' needed here? But I'm not an expert in English grammar...

> +	 * in enabled state at init.
> +	 * Now that someone is really trying to enable them,
> +	 * just update the state.
> +	 */
> +	if (oh->_state == _HWMOD_STATE_ENABLED_AT_INIT) {
> +		oh->_state = _HWMOD_STATE_ENABLED;
> +		return 0;
> +	}
> +
>   	if (oh->_state != _HWMOD_STATE_INITIALIZED&&
>   	oh->_state != _HWMOD_STATE_IDLE&&
>   	oh->_state != _HWMOD_STATE_DISABLED) {
> @@ -1449,7 +1460,6 @@ static int _enable(struct omap_hwmod *oh)
>   		return -EINVAL;
>   	}
>
> -

Not related to the patch changelog but that make senses to do it, so 
just update the changelog.

>   	/*
>   	 * If an IP contains only one HW reset line, then de-assert it in order
>   	 * to allow the module state transition. Otherwise the PRCM will return
> @@ -1744,8 +1754,10 @@ static int _setup(struct omap_hwmod *oh, void *data)
>   	 * it should be set by the core code as a runtime flag during startup
>   	 */
>   	if ((oh->flags&  HWMOD_INIT_NO_IDLE)&&
> -	    (postsetup_state == _HWMOD_STATE_IDLE))
> +	    (postsetup_state == _HWMOD_STATE_IDLE)) {
> +		oh->_state = _HWMOD_STATE_ENABLED_AT_INIT;
>   		postsetup_state = _HWMOD_STATE_ENABLED;
> +	}
>
>   	if (postsetup_state == _HWMOD_STATE_IDLE)
>   		_idle(oh);
> diff --git a/arch/arm/plat-omap/include/plat/omap_hwmod.h b/arch/arm/plat-omap/include/plat/omap_hwmod.h
> index 1b81dfb..cd49d60 100644
> --- a/arch/arm/plat-omap/include/plat/omap_hwmod.h
> +++ b/arch/arm/plat-omap/include/plat/omap_hwmod.h
> @@ -436,6 +436,7 @@ struct omap_hwmod_omap4_prcm {
>   #define _HWMOD_STATE_ENABLED			4
>   #define _HWMOD_STATE_IDLE			5
>   #define _HWMOD_STATE_DISABLED			6
> +#define _HWMOD_STATE_ENABLED_AT_INIT		7

You should update the comment before... yeah I know, the other states 
are not documented, but they are much more understandable than this new one.

>   /**
>    * struct omap_hwmod_class - the type of an IP block

+1 Looks good to me but someone else must approve...
Oops, sorry its not Gerrit :-)

Acked-by: Benoit Cousson <b-cousson@ti.com>

Thanks,
Benoit

Re: [PATCH] ARM: omap_hwmod: Add a new state to handle hwmods left enabled at init

[Rajendra Nayak]

On Thursday 17 November 2011 04:09 PM, Cousson, Benoit wrote:
> + Paul
>
> On 11/17/2011 11:11 AM, Rajendra Nayak wrote:
>> A hwmod with a 'HWMOD_INIT_NO_IDLE' flag set, is left in
>> enabled state by the hwmod framework post the initial setup.
>> Once a real user of the device (a driver) tries to enable it
>> at a later point, the hmwod framework throws a WARN() about
>
> typo: -------------------^
>
>> the device being already in enabled state.
>>
>> Fix this by introducing a new state '_HWMOD_STATE_ENABLED_AT_INIT'
>> to identify such devices/hwmods, so nothing but just a state
>> change to '_HWMOD_STATE_ENABLED' can be done when the device/hwmod
>> is requested to be enabled (the first time) by its driver/user.
>>
>> A good example of a such a device is an UART used as debug console.
>> The UART module needs to be kept enabled through the boot, until the
>> UART driver takes control of it, for debug prints to appear on
>> the console.
>>
>> Signed-off-by: Rajendra Nayak<rnayak@ti.com>
>> ---
>> arch/arm/mach-omap2/omap_hwmod.c | 16 ++++++++++++++--
>> arch/arm/plat-omap/include/plat/omap_hwmod.h | 1 +
>> 2 files changed, 15 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/arm/mach-omap2/omap_hwmod.c
>> b/arch/arm/mach-omap2/omap_hwmod.c
>> index d7f4623..7d94cc3 100644
>> --- a/arch/arm/mach-omap2/omap_hwmod.c
>> +++ b/arch/arm/mach-omap2/omap_hwmod.c
>> @@ -1441,6 +1441,17 @@ static int _enable(struct omap_hwmod *oh)
>>
>> pr_debug("omap_hwmod: %s: enabling\n", oh->name);
>>
>> + /*
>> + * hwmods' with HWMOD_INIT_NO_IDLE flag set, are left
>
> Is the ' needed here? But I'm not an expert in English grammar...

Me neither, lets ask Paul :)

>
>> + * in enabled state at init.
>> + * Now that someone is really trying to enable them,
>> + * just update the state.
>> + */
>> + if (oh->_state == _HWMOD_STATE_ENABLED_AT_INIT) {
>> + oh->_state = _HWMOD_STATE_ENABLED;
>> + return 0;
>> + }
>> +
>> if (oh->_state != _HWMOD_STATE_INITIALIZED&&
>> oh->_state != _HWMOD_STATE_IDLE&&
>> oh->_state != _HWMOD_STATE_DISABLED) {
>> @@ -1449,7 +1460,6 @@ static int _enable(struct omap_hwmod *oh)
>> return -EINVAL;
>> }
>>
>> -
>
> Not related to the patch changelog but that make senses to do it, so
> just update the changelog.

No, its just a stay change. I'll get rid of it.

>
>> /*
>> * If an IP contains only one HW reset line, then de-assert it in order
>> * to allow the module state transition. Otherwise the PRCM will return
>> @@ -1744,8 +1754,10 @@ static int _setup(struct omap_hwmod *oh, void
>> *data)
>> * it should be set by the core code as a runtime flag during startup
>> */
>> if ((oh->flags& HWMOD_INIT_NO_IDLE)&&
>> - (postsetup_state == _HWMOD_STATE_IDLE))
>> + (postsetup_state == _HWMOD_STATE_IDLE)) {
>> + oh->_state = _HWMOD_STATE_ENABLED_AT_INIT;
>> postsetup_state = _HWMOD_STATE_ENABLED;
>> + }
>>
>> if (postsetup_state == _HWMOD_STATE_IDLE)
>> _idle(oh);
>> diff --git a/arch/arm/plat-omap/include/plat/omap_hwmod.h
>> b/arch/arm/plat-omap/include/plat/omap_hwmod.h
>> index 1b81dfb..cd49d60 100644
>> --- a/arch/arm/plat-omap/include/plat/omap_hwmod.h
>> +++ b/arch/arm/plat-omap/include/plat/omap_hwmod.h
>> @@ -436,6 +436,7 @@ struct omap_hwmod_omap4_prcm {
>> #define _HWMOD_STATE_ENABLED 4
>> #define _HWMOD_STATE_IDLE 5
>> #define _HWMOD_STATE_DISABLED 6
>> +#define _HWMOD_STATE_ENABLED_AT_INIT 7
>
> You should update the comment before... yeah I know, the other states
> are not documented, but they are much more understandable than this new
> one.

Yeah, makes sense. Will add comments.

>
>> /**
>> * struct omap_hwmod_class - the type of an IP block
>
> +1 Looks good to me but someone else must approve...
> Oops, sorry its not Gerrit :-)
>
> Acked-by: Benoit Cousson <b-cousson@ti.com>
>
> Thanks,
> Benoit

Re: [PATCH] ARM: omap_hwmod: Add a new state to handle hwmods left enabled at init

[Govindraj]

On Thu, Nov 17, 2011 at 3:41 PM, Rajendra Nayak <rnayak@ti.com> wrote:
> A hwmod with a 'HWMOD_INIT_NO_IDLE' flag set, is left in
> enabled state by the hwmod framework post the initial setup.
> Once a real user of the device (a driver) tries to enable it
> at a later point, the hmwod framework throws a WARN() about
> the device being already in enabled state.
>
> Fix this by introducing a new state '_HWMOD_STATE_ENABLED_AT_INIT'
> to identify such devices/hwmods, so nothing but just a state
> change to '_HWMOD_STATE_ENABLED' can be done when the device/hwmod
> is requested to be enabled (the first time) by its driver/user.
>
> A good example of a such a device is an UART used as debug console.
> The UART module needs to be kept enabled through the boot, until the
> UART driver takes control of it, for debug prints to appear on
> the console.
>
> Signed-off-by: Rajendra Nayak <rnayak@ti.com>

tested with uart runtime v8 patch series works fine.
helps to simply the serial.c code without using custom console activate funcs.
thanks for handling this within the framework.

FWIW,

Tested-by: Govindraj.R <govindraj.raja@ti.com>

--
Thanks,
Govindraj.R


> ---
>  arch/arm/mach-omap2/omap_hwmod.c             |   16 ++++++++++++++--
>  arch/arm/plat-omap/include/plat/omap_hwmod.h |    1 +
>  2 files changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm/mach-omap2/omap_hwmod.c b/arch/arm/mach-omap2/omap_hwmod.c
> index d7f4623..7d94cc3 100644
> --- a/arch/arm/mach-omap2/omap_hwmod.c
> +++ b/arch/arm/mach-omap2/omap_hwmod.c
> @@ -1441,6 +1441,17 @@ static int _enable(struct omap_hwmod *oh)
>
>        pr_debug("omap_hwmod: %s: enabling\n", oh->name);
>
> +       /*
> +        * hwmods' with HWMOD_INIT_NO_IDLE flag set, are left
> +        * in enabled state at init.
> +        * Now that someone is really trying to enable them,
> +        * just update the state.
> +        */
> +       if (oh->_state == _HWMOD_STATE_ENABLED_AT_INIT) {
> +               oh->_state = _HWMOD_STATE_ENABLED;
> +               return 0;
> +       }
> +
>        if (oh->_state != _HWMOD_STATE_INITIALIZED &&
>            oh->_state != _HWMOD_STATE_IDLE &&
>            oh->_state != _HWMOD_STATE_DISABLED) {
> @@ -1449,7 +1460,6 @@ static int _enable(struct omap_hwmod *oh)
>                return -EINVAL;
>        }
>
> -
>        /*
>         * If an IP contains only one HW reset line, then de-assert it in order
>         * to allow the module state transition. Otherwise the PRCM will return
> @@ -1744,8 +1754,10 @@ static int _setup(struct omap_hwmod *oh, void *data)
>         * it should be set by the core code as a runtime flag during startup
>         */
>        if ((oh->flags & HWMOD_INIT_NO_IDLE) &&
> -           (postsetup_state == _HWMOD_STATE_IDLE))
> +           (postsetup_state == _HWMOD_STATE_IDLE)) {
> +               oh->_state = _HWMOD_STATE_ENABLED_AT_INIT;
>                postsetup_state = _HWMOD_STATE_ENABLED;
> +       }
>
>        if (postsetup_state == _HWMOD_STATE_IDLE)
>                _idle(oh);
> diff --git a/arch/arm/plat-omap/include/plat/omap_hwmod.h b/arch/arm/plat-omap/include/plat/omap_hwmod.h
> index 1b81dfb..cd49d60 100644
> --- a/arch/arm/plat-omap/include/plat/omap_hwmod.h
> +++ b/arch/arm/plat-omap/include/plat/omap_hwmod.h
> @@ -436,6 +436,7 @@ struct omap_hwmod_omap4_prcm {
>  #define _HWMOD_STATE_ENABLED                   4
>  #define _HWMOD_STATE_IDLE                      5
>  #define _HWMOD_STATE_DISABLED                  6
> +#define _HWMOD_STATE_ENABLED_AT_INIT           7
>
>  /**
>  * struct omap_hwmod_class - the type of an IP block
> --
> 1.7.1
>
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Re: [PATCH] ARM: omap_hwmod: Add a new state to handle hwmods left enabled at init

[Kevin Hilman]

Rajendra Nayak <rnayak@ti.com> writes:

> A hwmod with a 'HWMOD_INIT_NO_IDLE' flag set, is left in
> enabled state by the hwmod framework post the initial setup.
> Once a real user of the device (a driver) tries to enable it
> at a later point, the hmwod framework throws a WARN() about
> the device being already in enabled state.
>
> Fix this by introducing a new state '_HWMOD_STATE_ENABLED_AT_INIT'
> to identify such devices/hwmods, so nothing but just a state
> change to '_HWMOD_STATE_ENABLED' can be done when the device/hwmod
> is requested to be enabled (the first time) by its driver/user.
>
> A good example of a such a device is an UART used as debug console.
> The UART module needs to be kept enabled through the boot, until the
> UART driver takes control of it, for debug prints to appear on
> the console.

Nice.  This is indeed much cleaner than what we're doing in the UART
code.  However...

> Signed-off-by: Rajendra Nayak <rnayak@ti.com>
> ---
>  arch/arm/mach-omap2/omap_hwmod.c             |   16 ++++++++++++++--
>  arch/arm/plat-omap/include/plat/omap_hwmod.h |    1 +
>  2 files changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm/mach-omap2/omap_hwmod.c b/arch/arm/mach-omap2/omap_hwmod.c
> index d7f4623..7d94cc3 100644
> --- a/arch/arm/mach-omap2/omap_hwmod.c
> +++ b/arch/arm/mach-omap2/omap_hwmod.c
> @@ -1441,6 +1441,17 @@ static int _enable(struct omap_hwmod *oh)
>  
>  	pr_debug("omap_hwmod: %s: enabling\n", oh->name);
>  
> +	/*
> +	 * hwmods' with HWMOD_INIT_NO_IDLE flag set, are left

(no the ' isn't necessary)

> +	 * in enabled state at init.
> +	 * Now that someone is really trying to enable them,
> +	 * just update the state.
> +	 */
> +	if (oh->_state == _HWMOD_STATE_ENABLED_AT_INIT) {
> +		oh->_state = _HWMOD_STATE_ENABLED;
> +		return 0;
> +	}

...this subtly changes the behavior, at least compared to how the UART
code handles this today.

One thing that this doesn't do that the current UART code does is ensure
that the IP is actually in a state that can properly idle after this is
done.

For example, if the bootloader is dumb (most are) and has configured the
UARTs in mode that prevents idle (e.g. no-idle mode), then these UARTs
will never allow the SoC to hit low power states.

So, what's really needed is not just a return here, but an _idle() and
then continue so we know that the HW is in a state that we know can
idle from here on out.

Kevin

Re: [PATCH] ARM: omap_hwmod: Add a new state to handle hwmods left enabled at init

[Rajendra Nayak]

Hi Kevin,

On Friday 18 November 2011 01:05 AM, Kevin Hilman wrote:
> Rajendra Nayak<rnayak@ti.com>  writes:
>
>> A hwmod with a 'HWMOD_INIT_NO_IDLE' flag set, is left in
>> enabled state by the hwmod framework post the initial setup.
>> Once a real user of the device (a driver) tries to enable it
>> at a later point, the hmwod framework throws a WARN() about
>> the device being already in enabled state.
>>
>> Fix this by introducing a new state '_HWMOD_STATE_ENABLED_AT_INIT'
>> to identify such devices/hwmods, so nothing but just a state
>> change to '_HWMOD_STATE_ENABLED' can be done when the device/hwmod
>> is requested to be enabled (the first time) by its driver/user.
>>
>> A good example of a such a device is an UART used as debug console.
>> The UART module needs to be kept enabled through the boot, until the
>> UART driver takes control of it, for debug prints to appear on
>> the console.
>
> Nice.  This is indeed much cleaner than what we're doing in the UART
> code.  However...
>
>> Signed-off-by: Rajendra Nayak<rnayak@ti.com>
>> ---
>>   arch/arm/mach-omap2/omap_hwmod.c             |   16 ++++++++++++++--
>>   arch/arm/plat-omap/include/plat/omap_hwmod.h |    1 +
>>   2 files changed, 15 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/arm/mach-omap2/omap_hwmod.c b/arch/arm/mach-omap2/omap_hwmod.c
>> index d7f4623..7d94cc3 100644
>> --- a/arch/arm/mach-omap2/omap_hwmod.c
>> +++ b/arch/arm/mach-omap2/omap_hwmod.c
>> @@ -1441,6 +1441,17 @@ static int _enable(struct omap_hwmod *oh)
>>
>>   	pr_debug("omap_hwmod: %s: enabling\n", oh->name);
>>
>> +	/*
>> +	 * hwmods' with HWMOD_INIT_NO_IDLE flag set, are left
>
> (no the ' isn't necessary)
>
>> +	 * in enabled state at init.
>> +	 * Now that someone is really trying to enable them,
>> +	 * just update the state.
>> +	 */
>> +	if (oh->_state == _HWMOD_STATE_ENABLED_AT_INIT) {
>> +		oh->_state = _HWMOD_STATE_ENABLED;
>> +		return 0;
>> +	}
>
> ...this subtly changes the behavior, at least compared to how the UART
> code handles this today.
>
> One thing that this doesn't do that the current UART code does is ensure
> that the IP is actually in a state that can properly idle after this is
> done.
>
> For example, if the bootloader is dumb (most are) and has configured the
> UARTs in mode that prevents idle (e.g. no-idle mode), then these UARTs
> will never allow the SoC to hit low power states.
>
> So, what's really needed is not just a return here, but an _idle() and
> then continue so we know that the HW is in a state that we know can
> idle from here on out.

I don't know if I completely understand what you are saying.
The above change is in the _enable() call which would be triggered
as part of runtime call from the serial driver to enable the module.
(Since the module is already enabled, you just change state to suggest
its now enabled by its user, rather than 'left enabled' at init)
There would be another call from the serial driver to idle it when
a corresponding hwmod _idle() call would idle the device.
I don't seem to understand why would a call to _idle() be needed
in an _enable() call.

regards,
Rajendra

>
> Kevin

Re: [PATCH] ARM: omap_hwmod: Add a new state to handle hwmods left enabled at init

[Cousson, Benoit]

Hi Kevin and Rajendra,

On 11/18/2011 7:44 AM, Rajendra Nayak wrote:
> Hi Kevin,
>
> On Friday 18 November 2011 01:05 AM, Kevin Hilman wrote:
>> Rajendra Nayak<rnayak-l0cyMroinI0@public.gmane.org> writes:
>>
>>> A hwmod with a 'HWMOD_INIT_NO_IDLE' flag set, is left in
>>> enabled state by the hwmod framework post the initial setup.
>>> Once a real user of the device (a driver) tries to enable it
>>> at a later point, the hmwod framework throws a WARN() about
>>> the device being already in enabled state.
>>>
>>> Fix this by introducing a new state '_HWMOD_STATE_ENABLED_AT_INIT'
>>> to identify such devices/hwmods, so nothing but just a state
>>> change to '_HWMOD_STATE_ENABLED' can be done when the device/hwmod
>>> is requested to be enabled (the first time) by its driver/user.
>>>
>>> A good example of a such a device is an UART used as debug console.
>>> The UART module needs to be kept enabled through the boot, until the
>>> UART driver takes control of it, for debug prints to appear on
>>> the console.
>>
>> Nice. This is indeed much cleaner than what we're doing in the UART
>> code. However...
>>
>>> Signed-off-by: Rajendra Nayak<rnayak-l0cyMroinI0@public.gmane.org>
>>> ---
>>> arch/arm/mach-omap2/omap_hwmod.c | 16 ++++++++++++++--
>>> arch/arm/plat-omap/include/plat/omap_hwmod.h | 1 +
>>> 2 files changed, 15 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/arch/arm/mach-omap2/omap_hwmod.c
>>> b/arch/arm/mach-omap2/omap_hwmod.c
>>> index d7f4623..7d94cc3 100644
>>> --- a/arch/arm/mach-omap2/omap_hwmod.c
>>> +++ b/arch/arm/mach-omap2/omap_hwmod.c
>>> @@ -1441,6 +1441,17 @@ static int _enable(struct omap_hwmod *oh)
>>>
>>> pr_debug("omap_hwmod: %s: enabling\n", oh->name);
>>>
>>> + /*
>>> + * hwmods' with HWMOD_INIT_NO_IDLE flag set, are left
>>
>> (no the ' isn't necessary)
>>
>>> + * in enabled state at init.
>>> + * Now that someone is really trying to enable them,
>>> + * just update the state.
>>> + */
>>> + if (oh->_state == _HWMOD_STATE_ENABLED_AT_INIT) {
>>> + oh->_state = _HWMOD_STATE_ENABLED;
>>> + return 0;
>>> + }
>>
>> ...this subtly changes the behavior, at least compared to how the UART
>> code handles this today.
>>
>> One thing that this doesn't do that the current UART code does is ensure
>> that the IP is actually in a state that can properly idle after this is
>> done.
>>
>> For example, if the bootloader is dumb (most are) and has configured the
>> UARTs in mode that prevents idle (e.g. no-idle mode), then these UARTs
>> will never allow the SoC to hit low power states.

That will not happen because we already did the complete enable sequence 
during setup phase that will set the sysconfig properly.
So the device is properly initialized, we just skipped the idle phase 
because we wanted to keep the device operational for the console.

>> So, what's really needed is not just a return here, but an _idle() and
>> then continue so we know that the HW is in a state that we know can
>> idle from here on out.

We are in the enable call, so the driver / omap_device does expect the 
IP to be operational at the moment, we cannot put it into idle.

> I don't know if I completely understand what you are saying.
> The above change is in the _enable() call which would be triggered
> as part of runtime call from the serial driver to enable the module.
> (Since the module is already enabled, you just change state to suggest
> its now enabled by its user, rather than 'left enabled' at init)
> There would be another call from the serial driver to idle it when
> a corresponding hwmod _idle() call would idle the device.
> I don't seem to understand why would a call to _idle() be needed
> in an _enable() call.

Yep, I agree. I think Kevin's point is due to the previous sequence used 
by the uart:

+	omap_hwmod_idle(od->hwmods[0]);
+	omap_hwmod_enable(od->hwmods[0]);

But that sequence is not needed for my point of view. The device is 
already properly enabled. I don't think it was even needed in the 
previous code. The hwmod was already enabled properly, only the 
omap_device was disabled. So the original omap_console_hwmod_enable 
should just do nothing.

Regards,
Benoit

Re: [PATCH] ARM: omap_hwmod: Add a new state to handle hwmods left enabled at init

[Kevin Hilman]

"Cousson, Benoit" <b-cousson@ti.com> writes:

> Hi Kevin and Rajendra,
>
> On 11/18/2011 7:44 AM, Rajendra Nayak wrote:
>> Hi Kevin,
>>
>> On Friday 18 November 2011 01:05 AM, Kevin Hilman wrote:
>>> Rajendra Nayak<rnayak@ti.com> writes:
>>>
>>>> A hwmod with a 'HWMOD_INIT_NO_IDLE' flag set, is left in
>>>> enabled state by the hwmod framework post the initial setup.
>>>> Once a real user of the device (a driver) tries to enable it
>>>> at a later point, the hmwod framework throws a WARN() about
>>>> the device being already in enabled state.
>>>>
>>>> Fix this by introducing a new state '_HWMOD_STATE_ENABLED_AT_INIT'
>>>> to identify such devices/hwmods, so nothing but just a state
>>>> change to '_HWMOD_STATE_ENABLED' can be done when the device/hwmod
>>>> is requested to be enabled (the first time) by its driver/user.
>>>>
>>>> A good example of a such a device is an UART used as debug console.
>>>> The UART module needs to be kept enabled through the boot, until the
>>>> UART driver takes control of it, for debug prints to appear on
>>>> the console.
>>>
>>> Nice. This is indeed much cleaner than what we're doing in the UART
>>> code. However...
>>>
>>>> Signed-off-by: Rajendra Nayak<rnayak@ti.com>
>>>> ---
>>>> arch/arm/mach-omap2/omap_hwmod.c | 16 ++++++++++++++--
>>>> arch/arm/plat-omap/include/plat/omap_hwmod.h | 1 +
>>>> 2 files changed, 15 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/arch/arm/mach-omap2/omap_hwmod.c
>>>> b/arch/arm/mach-omap2/omap_hwmod.c
>>>> index d7f4623..7d94cc3 100644
>>>> --- a/arch/arm/mach-omap2/omap_hwmod.c
>>>> +++ b/arch/arm/mach-omap2/omap_hwmod.c
>>>> @@ -1441,6 +1441,17 @@ static int _enable(struct omap_hwmod *oh)
>>>>
>>>> pr_debug("omap_hwmod: %s: enabling\n", oh->name);
>>>>
>>>> + /*
>>>> + * hwmods' with HWMOD_INIT_NO_IDLE flag set, are left
>>>
>>> (no the ' isn't necessary)
>>>
>>>> + * in enabled state at init.
>>>> + * Now that someone is really trying to enable them,
>>>> + * just update the state.
>>>> + */
>>>> + if (oh->_state == _HWMOD_STATE_ENABLED_AT_INIT) {
>>>> + oh->_state = _HWMOD_STATE_ENABLED;
>>>> + return 0;
>>>> + }
>>>
>>> ...this subtly changes the behavior, at least compared to how the UART
>>> code handles this today.
>>>
>>> One thing that this doesn't do that the current UART code does is ensure
>>> that the IP is actually in a state that can properly idle after this is
>>> done.
>>>
>>> For example, if the bootloader is dumb (most are) and has configured the
>>> UARTs in mode that prevents idle (e.g. no-idle mode), then these UARTs
>>> will never allow the SoC to hit low power states.
>
> That will not happen because we already did the complete enable
> sequence during setup phase that will set the sysconfig properly.
> So the device is properly initialized, we just skipped the idle phase
> because we wanted to keep the device operational for the console.

Ah, perfect.

>>> So, what's really needed is not just a return here, but an _idle() and
>>> then continue so we know that the HW is in a state that we know can
>>> idle from here on out.
>
> We are in the enable call, so the driver / omap_device does expect the
> IP to be operational at the moment, we cannot put it into idle.
>
>> I don't know if I completely understand what you are saying.
>> The above change is in the _enable() call which would be triggered
>> as part of runtime call from the serial driver to enable the module.
>> (Since the module is already enabled, you just change state to suggest
>> its now enabled by its user, rather than 'left enabled' at init)
>> There would be another call from the serial driver to idle it when
>> a corresponding hwmod _idle() call would idle the device.
>> I don't seem to understand why would a call to _idle() be needed
>> in an _enable() call.
>
> Yep, I agree. I think Kevin's point is due to the previous sequence
> used by the uart:
>
> +	omap_hwmod_idle(od->hwmods[0]);
> +	omap_hwmod_enable(od->hwmods[0]);
>
> But that sequence is not needed for my point of view. The device is
> already properly enabled. I don't think it was even needed in the
> previous code. The hwmod was already enabled properly, only the
> omap_device was disabled. So the original omap_console_hwmod_enable
> should just do nothing.

OK, thanks for the clarification.

In that case, this patch

Acked-by: Kevin Hilman <khilman@ti.com>

Kevin