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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
