On Wed, Feb 20, 2019 at 05:42:28PM +0100, Hans de Goede wrote: > > > The input-current-limit only specifies how much current the charger may > > > draw from the micro-usb for both supplying the laptop as well as for > > > charging the battery combined. You can safely set this as high as > > > the charger can handle (2A for a dedicated charger). > > > > > > The BQ25892 should have a *separate* setting for the max current to > > > use while charging the battery (assuming that the input current allows > > > drawing enough current in the first place). I would hope that those bits > > > have some sane value set from the firmware... > > > > Yes, the charger has separate battery current limit but firmware doesn't > > change its default value (2048 mA) while Lenovo's software driver does. > > It set battery charging limit to 4 A and input limit to 2 A (it makes > > sense because Lenovo adapter and BQ25892 both support voltage increasing > > upto 12V). > > Hmm, I guess your device uses a separate power-barrel charging conector > then? 12v over micro-usb requires special negotiation which the Whiskey Cove > PMIC does not support AFAIK.
The Yoga Book supports kind of quick charging by negotiate voltage with 'current pulse protocol' supported by BQ25892 and Lenovo's wall cube. I think that PMIC is not connected to VBUS directly. After charging started, BQ25892 driver can ask power adapter to increase voltage number of times upto 12V. See https://github.com/jekhor/yogabook-linux-kernel/blob/master/drivers/power/supply/bq25890_charger.c#L918 for example. > > In either case if you want to increase the max battery current to 4A > in the kernel, then this will have to be guarded by a DMI check. Yes. > > I beieve the way to do this wuld be throuh a device-property on the > charger which gets set from drivers/i2c/busses/i2c-cht-wc.c, but as > said this needs to be behind a DMI check, e cannot just g and boost > the max charge current to 4A everywhere. Yes, I use such method already in the my kernel: https://github.com/jekhor/yogabook-linux-kernel/blob/master/drivers/i2c/busses/i2c-cht-wc.c#L247 Anyway, charger tweaking will be next iteration, now I want to complete current extcon stuff/ > Regards, > > Hans -- Yauhen Kharuzhy
