Re: [PATCH v2 2/4] Revert "drm/panel-edp: Add SDC ATNA45AF01"

[Neil Armstrong]

On 15/07/2024 14:54, Stephan Gerhold wrote:
> On Mon, Jul 15, 2024 at 02:42:12PM +0200, Neil Armstrong wrote:
> > On 15/07/2024 14:15, Stephan Gerhold wrote:
> > > This reverts commit 8ebb1fc2e69ab8b89a425e402c7bd85e053b7b01.
> > >
> > > The panel should be handled through the samsung-atna33xc20 driver for
> > > correct power up timings. Otherwise the backlight does not work correctly.
> > >
> > > We have existing users of this panel through the generic "edp-panel"
> > > compatible (e.g. the Qualcomm X1E80100 CRD), but the screen works only
> > > partially in that configuration: It works after boot but once the screen
> > > gets disabled it does not turn on again until after reboot. It behaves the
> > > same way with the default "conservative" timings, so we might as well drop
> > > the configuration from the panel-edp driver. That way, users with old DTBs
> > > will get a warning and can move to the new driver.
> > >
> > > Reviewed-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
> > > Signed-off-by: Stephan Gerhold <stephan.gerhold@xxxxxxxxxx>
> > > ---
> > >    drivers/gpu/drm/panel/panel-edp.c | 2 --
> > >    1 file changed, 2 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/panel/panel-edp.c b/drivers/gpu/drm/panel/panel-edp.c
> > > index 3a574a9b46e7..d2d682385e89 100644
> > > --- a/drivers/gpu/drm/panel/panel-edp.c
> > > +++ b/drivers/gpu/drm/panel/panel-edp.c
> > > @@ -1960,8 +1960,6 @@ static const struct edp_panel_entry edp_panels[] = {
> > >    	EDP_PANEL_ENTRY('L', 'G', 'D', 0x05af, &delay_200_500_e200_d200, "Unknown"),
> > >    	EDP_PANEL_ENTRY('L', 'G', 'D', 0x05f1, &delay_200_500_e200_d200, "Unknown"),
> > > -	EDP_PANEL_ENTRY('S', 'D', 'C', 0x416d, &delay_100_500_e200, "ATNA45AF01"),
> > > -
> > >    	EDP_PANEL_ENTRY('S', 'H', 'P', 0x1511, &delay_200_500_e50, "LQ140M1JW48"),
> > >    	EDP_PANEL_ENTRY('S', 'H', 'P', 0x1523, &delay_80_500_e50, "LQ140M1JW46"),
> > >    	EDP_PANEL_ENTRY('S', 'H', 'P', 0x153a, &delay_200_500_e50, "LQ140T1JH01"),
> >
> > How will we handle current/old crd DT with new kernels ?
>
> I think this is answered in the commit message:
>
> > > We have existing users of this panel through the generic "edp-panel"
> > > compatible (e.g. the Qualcomm X1E80100 CRD), but the screen works only
> > > partially in that configuration: It works after boot but once the screen
> > > gets disabled it does not turn on again until after reboot. It behaves the
> > > same way with the default "conservative" timings, so we might as well drop
> > > the configuration from the panel-edp driver. That way, users with old DTBs
> > > will get a warning and can move to the new driver.
>
> Basically with the entry removed, the panel-edp driver will fallback to
> default "conservative" timings when using old DTBs. There will be a
> warning in dmesg, but otherwise the panel will somewhat work just as
> before. I think this is a good way to remind users to upgrade.

I consider this as a regression

> > Same question for patch 3, thie serie introduces a bindings that won't be valid
> > if we backport patch 3. I don't think patch should be backported, and this patch
> > should be dropped.
>
> There would be a dtbs_check warning, yeah. Functionally, it would work
> just fine. Is that reason enough to keep display partially broken for
> 6.11? We could also apply the minor binding change for 6.11 if needed.

I don't know how to answer this, I'll let the DT maintainer comment this.

The problem is I do not think we can pass the whole patchset as fixes
for v6.11, patches 2 & 3 could, patches 1 & 4 definitely can't.

Neil

> I'm also fine if this just goes into 6.12 though.
>
> Thanks,
> Stephan