Re: [PATCH] power: supply: sbs-battery: chromebook workaround for PEC

["Milan P. Stanić" <mps@arvanta.net>]

Hi all,

On Mon, 2020-10-05 at 19:53, Vicente Bergas wrote:
> On Monday, October 5, 2020 12:46:01 AM CEST, Sebastian Reichel wrote:
> > Looks like the I2C tunnel implementation from Chromebook's
> > embedded controller does not handle PEC correctly. Fix this
> > by disabling PEC for batteries behind those I2C tunnels as
> > a workaround.
> > 
> > Reported-by: "Milan P. Stanić" <mps@arvanta.net>
> > Reported-by: Vicente Bergas <vicencb@gmail.com>
> > CC: Enric Balletbo i Serra <enric.balletbo@collabora.com>
> > Fixes: 7222bd603dd2 ("power: supply: sbs-battery: add PEC support")
> > Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
> > ---
> > Hi,
> > 
> > This is compile-tested only, since I do not have a chromebook at
> > hand. Please test if this fixes your issue.
> 
> Hi Sebastian,
> tested on rk3399-gru-kevin with 5.9.0-rc8 and now the CPU usage is 0 when
> idling.
> dmesg reports:
> [    1.370249] sbs-battery 9-000b: Disabling PEC because of broken Cros-EC
> implementation

Also I tested on same board and same kernel version and can confirm
this.
 
> So,
> Tested-by: Vicente Bergas <vicencb@gmail.com>
> 
> Thanks,
>  Vicente.
> 
> > -- Sebastian
> > ---
> >  drivers/power/supply/sbs-battery.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git a/drivers/power/supply/sbs-battery.c
> > b/drivers/power/supply/sbs-battery.c
> > index 13192cbcce71..b6a538ebb378 100644
> > --- a/drivers/power/supply/sbs-battery.c
> > +++ b/drivers/power/supply/sbs-battery.c
> > @@ -279,6 +279,12 @@ static int sbs_update_presence(struct sbs_info
> > *chip, bool is_present)
> >  	else
> >  		client->flags &= ~I2C_CLIENT_PEC;
> >   +	if (of_device_is_compatible(client->dev.parent->of_node,
> > "google,cros-ec-i2c-tunnel")
> > +	    && client->flags & I2C_CLIENT_PEC) {
> > +		dev_info(&client->dev, "Disabling PEC because of broken Cros-EC
> > implementation\n");
> > +		client->flags &= ~I2C_CLIENT_PEC;
> > +	}
> > +
> >  	dev_dbg(&client->dev, "PEC: %s\n", (client->flags & I2C_CLIENT_PEC) ?
> >  		"enabled" : "disabled");
>