Re: [PATCH v2 2/2] extcon intel-cht-wc: Enable external charger

[Hans de Goede]

Hi,

On 20-02-19 22:24, Yauhen Kharuzhy wrote:
> ÑÑ, 20 ÑÐÐÑ. 2019 Ð. Ð 18:53, Hans de Goede <hdegoede@xxxxxxxxxx>:
> > Hi,
> >
> > On 2/19/19 10:24 PM, Yauhen Kharuzhy wrote:
> > > In some configuration external charger "#charge enable" signal is
> > > connected to PMIC. Enable it at device probing to allow charging.
> > >
> > > Save CHGRCTRL0 and CHGDISCTR registers at driver probing and restore
> > > them at driver unbind to re-enable hardware charging control if it was
> > > enabled before.
> > >
> > > Tested at Lenovo Yoga Book (YB1-X91L).

<snip>

> > > @@ -400,6 +487,7 @@ static int cht_wc_extcon_probe(struct platform_device *pdev)
> > >
> > >    disable_sw_control:
> > >        cht_wc_extcon_sw_control(ext, false);
> > > +     cht_wc_restore_initial_state(ext);
> >
> > The restore_initial_state will clober al changes made by the
> > cht_wc_extcon_sw_control call, so we do not need both. Thinking a bit
> > more about this I think it might be best to drop the state save/restore
> > code and just enable hw-control on exit unconditionally. We cannot be
> > sure that te initial state is sane, so just switching to hw-control on
> > exit seem best and requires less code.  Andy, what is your take on this?
>
> On the other hand we don't know if HW mode is suitable for given
> hardware configuration.
>
> We can suppose that if existing code with unconditionally switching to
> HW mode didn't cause
> any issues before than we can safely leave this for future discussions
> and add CHGDISCTRL restoring only.

The code would be a lot simpler if we also unconditionally put the chrgdis
pin back in hw control mode, then we only need your modifications to
cht_wc_extcon_sw_control() and we don't need the save / restore state
functions.

On my hardware with a whiskey cove PMIC the firmware comes up with 0x50 in
the CHGDISCTRL register, which means it is under hw control, so we would
normally end up restoring that. I believe your Yoga Book is similar, so
there really is no need for the save / restore state functions.

Regards,

Hans