linux-kernel - Re: [PATCH 3/3] drm-panel: If drm_panel_dp_aux_backlight() fails, don't fail panel probe

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Message-ID: <CAD=FV=X1MRRdeP36j3SF3Wrp+iwd5R9aUKHDSbp38Hg6Pni-aw@mail.gmail.com>
Date: Sun, 7 Apr 2024 23:55:34 -0700
From: Doug Anderson <dianders@...omium.org>
To: Hsin-Yi Wang <hsinyi@...omium.org>
Cc: dri-devel@...ts.freedesktop.org, Pin-yen Lin <treapking@...omium.org>, 
	Prahlad Kilambi <prahladk@...gle.com>, Daniel Vetter <daniel@...ll.ch>, David Airlie <airlied@...il.com>, 
	Jessica Zhang <quic_jesszhan@...cinc.com>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Neil Armstrong <neil.armstrong@...aro.org>, Sam Ravnborg <sam@...nborg.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] drm-panel: If drm_panel_dp_aux_backlight() fails,
 don't fail panel probe

Hi,

On Mon, Mar 25, 2024 at 5:07 PM Hsin-Yi Wang <hsinyi@...omium.org> wrote:
>
> On Mon, Mar 25, 2024 at 2:57 PM Douglas Anderson <dianders@...omium.org> wrote:
> >
> > If we're using the AUX channel for eDP backlight and it fails to probe
> > for some reason, let's _not_ fail the panel probe.
> >
> > At least one case where we could fail to init the backlight is because
> > of a dead or physically missing panel. As talked about in detail in
> > the earlier patch in this series, ("drm/panel-edp: If we fail to
> > powerup/get EDID, use conservative timings"), this can cause the
> > entire system's display pipeline to fail to come up and that's
> > non-ideal.
> >
> > If we fail to init the backlight for some transitory reason, we should
> > dig in and see if there's a way to fix this (perhaps retries?). Even
> > in that case, though, having a panel whose backlight is stuck at 100%
> > (the default, at least in the panel Samsung ATNA33XC20 I tested) is
> > better than having no panel at all.
> >
> > Signed-off-by: Douglas Anderson <dianders@...omium.org>
>
> Reviewed-by: Hsin-Yi Wang <hsinyi@...omium.org>

Pushed to drm-misc-next:

b48ccb18e642 drm-panel: If drm_panel_dp_aux_backlight() fails, don't
fail panel probe