bq24190: What's the correct API to turn boost mode (OTG) on for the battery charger ?

bq24190: What's the correct API to turn boost mode (OTG) on for the battery charger ?

[Laurent Pinchart]

Hello,

I'm trying to enable battery charging on an OMAP4 board based on a twl6030 
PMIC with external bq24190 battery charger and bq27510 fuel gauge.

The system has an OTG USB port that can be used to charge the battery, and 
that can also be used in host mode. In that case the bq24190 needs to be 
switched to boost mode to provide the +5V power supply from the battery.

The bq24190 has a charge configuration register field that supports charge 
disabled, charge enabled and OTG (boost mode). The field is set by the bq24190 
driver in response to setting the charge type : POWER_SUPPLY_CHARGE_TYPE_NONE 
will disable charing, and POWER_SUPPLY_CHARGE_TYPE_TRICKLE and 
POWER_SUPPLY_CHARGE_TYPE_FAST will enable it. However, OTG boost mode is not 
supported.

The driver exposes most register fields as sysfs attributes (which doesn't 
sound very safe to me, but that's another story). I can thus enable OTG boost 
mode directly from userspace through the driver-specific API, but that just 
bypasses the power supply API. I'm thus not very fond of that solution.

Possibly due to my really basic (not to say nonexistent) knowledge of the 
power supply subsystem I haven't found an API to expose this feature. I was 
wondering if someone had given a though regarding how to implement this 
properly.

-- 
Regards,

Laurent Pinchart

Re: bq24190: What's the correct API to turn boost mode (OTG) on for the battery charger ?

[Mark A. Greer]

On Thu, May 15, 2014 at 10:29:26PM +0200, Laurent Pinchart wrote:
> Hello,

[Adding Anton Vorontsov to CC list.]

Hi Laurent.

> I'm trying to enable battery charging on an OMAP4 board based on a twl6030 
> PMIC with external bq24190 battery charger and bq27510 fuel gauge.
> 
> The system has an OTG USB port that can be used to charge the battery, and 
> that can also be used in host mode. In that case the bq24190 needs to be 
> switched to boost mode to provide the +5V power supply from the battery.
> 
> The bq24190 has a charge configuration register field that supports charge 
> disabled, charge enabled and OTG (boost mode). The field is set by the bq24190 
> driver in response to setting the charge type : POWER_SUPPLY_CHARGE_TYPE_NONE 
> will disable charing, and POWER_SUPPLY_CHARGE_TYPE_TRICKLE and 
> POWER_SUPPLY_CHARGE_TYPE_FAST will enable it. However, OTG boost mode is not 
> supported.


> 
> The driver exposes most register fields as sysfs attributes (which doesn't 
> sound very safe to me, but that's another story). I can thus enable OTG boost 
> mode directly from userspace through the driver-specific API, but that just 
> bypasses the power supply API. I'm thus not very fond of that solution.

No, its not a good solution.  As indicated in the commit log, the sysfs
entries are there because there are just so many fields that don't map
well to the existing interface.

Maybe we should add support for a DT entry to enable exporting those
fields(disabled by default)?

> Possibly due to my really basic (not to say nonexistent) knowledge of the 
> power supply subsystem I haven't found an API to expose this feature. I was 
> wondering if someone had given a though regarding how to implement this 
> properly.

What if we just added something like POWER_SUPPLY_CHARGE_TYPE_BOOST?

Mark
--

Re: bq24190: What's the correct API to turn boost mode (OTG) on for the battery charger ?

[Laurent Pinchart]

Hi Mark,

Thank you for the quick reply.

On Thursday 15 May 2014 15:08:44 Mark A. Greer wrote:
> On Thu, May 15, 2014 at 10:29:26PM +0200, Laurent Pinchart wrote:
> > Hello,
> 
> [Adding Anton Vorontsov to CC list.]
> 
> Hi Laurent.
> 
> > I'm trying to enable battery charging on an OMAP4 board based on a twl6030
> > PMIC with external bq24190 battery charger and bq27510 fuel gauge.
> > 
> > The system has an OTG USB port that can be used to charge the battery, and
> > that can also be used in host mode. In that case the bq24190 needs to be
> > switched to boost mode to provide the +5V power supply from the battery.
> > 
> > The bq24190 has a charge configuration register field that supports charge
> > disabled, charge enabled and OTG (boost mode). The field is set by the
> > bq24190 driver in response to setting the charge type :
> > POWER_SUPPLY_CHARGE_TYPE_NONE will disable charing, and
> > POWER_SUPPLY_CHARGE_TYPE_TRICKLE and
> > POWER_SUPPLY_CHARGE_TYPE_FAST will enable it. However, OTG boost mode is
> > not supported.
> > 
> > 
> > The driver exposes most register fields as sysfs attributes (which doesn't
> > sound very safe to me, but that's another story). I can thus enable OTG
> > boost mode directly from userspace through the driver-specific API, but
> > that just bypasses the power supply API. I'm thus not very fond of that
> > solution.
>
> No, its not a good solution.  As indicated in the commit log, the sysfs
> entries are there because there are just so many fields that don't map
> well to the existing interface.
> 
> Maybe we should add support for a DT entry to enable exporting those
> fields(disabled by default)?
> 
> > Possibly due to my really basic (not to say nonexistent) knowledge of the
> > power supply subsystem I haven't found an API to expose this feature. I
> > was wondering if someone had given a though regarding how to implement
> > this properly.
> 
> What if we just added something like POWER_SUPPLY_CHARGE_TYPE_BOOST?

That was actually my first thought, and I assumed it would be rejected as 
boost mode is not a charge type but a discharge type :-) This being said, I 
don't have enough experience with battery chargers to decide whether this is a 
good solution. If you believe it is, I'll trust you on that.

On a side note, is there any reference userspace implementation of a battery 
manager ? The vendor BSP I've received with the board hardcodes calls to the 
bq24190 in the MUSB driver to switch between OTG and trickle charge modes 
based on USB cable connection/disconnection events. That's pretty ugly, and I 
assume this should be handled in userspace - or is there a standard kernel 
infrastructure for that ? 

-- 
Regards,

Laurent Pinchart

Re: bq24190: What's the correct API to turn boost mode (OTG) on for the battery charger ?

[Mark A. Greer]

On Fri, May 16, 2014 at 12:35:34AM +0200, Laurent Pinchart wrote:
> Hi Mark,
> 
> Thank you for the quick reply.

Hi Laurent.  Sorry for the delay.

> On Thursday 15 May 2014 15:08:44 Mark A. Greer wrote:
> > On Thu, May 15, 2014 at 10:29:26PM +0200, Laurent Pinchart wrote:
> > > Hello,
> > 
> > [Adding Anton Vorontsov to CC list.]
> > 
> > Hi Laurent.
> > 
> > > I'm trying to enable battery charging on an OMAP4 board based on a twl6030
> > > PMIC with external bq24190 battery charger and bq27510 fuel gauge.
> > > 
> > > The system has an OTG USB port that can be used to charge the battery, and
> > > that can also be used in host mode. In that case the bq24190 needs to be
> > > switched to boost mode to provide the +5V power supply from the battery.
> > > 
> > > The bq24190 has a charge configuration register field that supports charge
> > > disabled, charge enabled and OTG (boost mode). The field is set by the
> > > bq24190 driver in response to setting the charge type :
> > > POWER_SUPPLY_CHARGE_TYPE_NONE will disable charing, and
> > > POWER_SUPPLY_CHARGE_TYPE_TRICKLE and
> > > POWER_SUPPLY_CHARGE_TYPE_FAST will enable it. However, OTG boost mode is
> > > not supported.
> > > 
> > > 
> > > The driver exposes most register fields as sysfs attributes (which doesn't
> > > sound very safe to me, but that's another story). I can thus enable OTG
> > > boost mode directly from userspace through the driver-specific API, but
> > > that just bypasses the power supply API. I'm thus not very fond of that
> > > solution.
> >
> > No, its not a good solution.  As indicated in the commit log, the sysfs
> > entries are there because there are just so many fields that don't map
> > well to the existing interface.
> > 
> > Maybe we should add support for a DT entry to enable exporting those
> > fields(disabled by default)?
> > 
> > > Possibly due to my really basic (not to say nonexistent) knowledge of the
> > > power supply subsystem I haven't found an API to expose this feature. I
> > > was wondering if someone had given a though regarding how to implement
> > > this properly.
> > 
> > What if we just added something like POWER_SUPPLY_CHARGE_TYPE_BOOST?
> 
> That was actually my first thought, and I assumed it would be rejected as 
> boost mode is not a charge type but a discharge type :-)

Er, right.  :(

> This being said, I 
> don't have enough experience with battery chargers to decide whether this is a 
> good solution. If you believe it is, I'll trust you on that.

No, you're right, that isn't a good solution.

I don't see a really good fit anywhere.  The easiest thing may be to add
a new POWER_SUPPLY_PROP_xxx power_supply_property member which can be set
to flip it into boost mode but I'm not sure if that's really the right
thing to do.

I hope Anton will comment on this.

> On a side note, is there any reference userspace implementation of a battery 
> manager ? The vendor BSP I've received with the board hardcodes calls to the 
> bq24190 in the MUSB driver to switch between OTG and trickle charge modes 
> based on USB cable connection/disconnection events. That's pretty ugly, and I 
> assume this should be handled in userspace - or is there a standard kernel 
> infrastructure for that ? 

I don't have a good feel for what's out there but the charger-manager may
be a good place to start:

Documentation/power/charger-manager.txt
drivers/power/charger-manager.c

HTH,

Mark
--

Re: bq24190: What's the correct API to turn boost mode (OTG) on for the battery charger ?

[Mark A. Greer]

On Wed, May 21, 2014 at 11:25:43AM -0700, Mark A. Greer wrote:
> On Fri, May 16, 2014 at 12:35:34AM +0200, Laurent Pinchart wrote:

> > On a side note, is there any reference userspace implementation of a battery 
> > manager ? The vendor BSP I've received with the board hardcodes calls to the 
> > bq24190 in the MUSB driver to switch between OTG and trickle charge modes 
> > based on USB cable connection/disconnection events. That's pretty ugly, and I 
> > assume this should be handled in userspace - or is there a standard kernel 
> > infrastructure for that ? 
> 
> I don't have a good feel for what's out there but the charger-manager may
> be a good place to start:
> 
> Documentation/power/charger-manager.txt
> drivers/power/charger-manager.c

And,

http://elinux.org/images/c/c6/Elce11_ham.pdf

Re: bq24190: What's the correct API to turn boost mode (OTG) on for the battery charger ?

[Mark A. Greer]

[Removing Anton from CC]

On Wed, May 21, 2014 at 11:25:43AM -0700, Mark A. Greer wrote:
> On Fri, May 16, 2014 at 12:35:34AM +0200, Laurent Pinchart wrote:
> > Hi Mark,
> > 
> > Thank you for the quick reply.
> 
> Hi Laurent.  Sorry for the delay.
> 
> > On Thursday 15 May 2014 15:08:44 Mark A. Greer wrote:
> > > On Thu, May 15, 2014 at 10:29:26PM +0200, Laurent Pinchart wrote:
> > > > Hello,
> > > 
> > > [Adding Anton Vorontsov to CC list.]
> > > 
> > > Hi Laurent.
> > > 
> > > > I'm trying to enable battery charging on an OMAP4 board based on a twl6030
> > > > PMIC with external bq24190 battery charger and bq27510 fuel gauge.
> > > > 
> > > > The system has an OTG USB port that can be used to charge the battery, and
> > > > that can also be used in host mode. In that case the bq24190 needs to be
> > > > switched to boost mode to provide the +5V power supply from the battery.
> > > > 
> > > > The bq24190 has a charge configuration register field that supports charge
> > > > disabled, charge enabled and OTG (boost mode). The field is set by the
> > > > bq24190 driver in response to setting the charge type :
> > > > POWER_SUPPLY_CHARGE_TYPE_NONE will disable charing, and
> > > > POWER_SUPPLY_CHARGE_TYPE_TRICKLE and
> > > > POWER_SUPPLY_CHARGE_TYPE_FAST will enable it. However, OTG boost mode is
> > > > not supported.
> > > > 
> > > > 
> > > > The driver exposes most register fields as sysfs attributes (which doesn't
> > > > sound very safe to me, but that's another story). I can thus enable OTG
> > > > boost mode directly from userspace through the driver-specific API, but
> > > > that just bypasses the power supply API. I'm thus not very fond of that
> > > > solution.
> > >
> > > No, its not a good solution.  As indicated in the commit log, the sysfs
> > > entries are there because there are just so many fields that don't map
> > > well to the existing interface.
> > > 
> > > Maybe we should add support for a DT entry to enable exporting those
> > > fields(disabled by default)?
> > > 
> > > > Possibly due to my really basic (not to say nonexistent) knowledge of the
> > > > power supply subsystem I haven't found an API to expose this feature. I
> > > > was wondering if someone had given a though regarding how to implement
> > > > this properly.
> > > 
> > > What if we just added something like POWER_SUPPLY_CHARGE_TYPE_BOOST?
> > 
> > That was actually my first thought, and I assumed it would be rejected as 
> > boost mode is not a charge type but a discharge type :-)
> 
> Er, right.  :(
> 
> > This being said, I 
> > don't have enough experience with battery chargers to decide whether this is a 
> > good solution. If you believe it is, I'll trust you on that.
> 
> No, you're right, that isn't a good solution.
> 
> I don't see a really good fit anywhere.  The easiest thing may be to add
> a new POWER_SUPPLY_PROP_xxx power_supply_property member which can be set
> to flip it into boost mode but I'm not sure if that's really the right
> thing to do.
> 
> I hope Anton will comment on this.

After looking at MAINTAINERS and its git log, it looks like Dmitry has
taken over.

Dmitry, do you have anything insight?

Mark
--