Messages in this thread | | | Subject | Re: [PATCH 2/2] extcon intel-cht-wc: Enable external charger | From | Hans de Goede <> | Date | Thu, 21 Feb 2019 10:33:38 +0100 |
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Hi,
On 20-02-19 21:28, Yauhen Kharuzhy wrote: > 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/
Ok, sounds good.
Regards,
Hans
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