[Intel-gfx] [PATCH] drm/i915/display/vlv_dsi: Do no shut down displays on reboot if a DSI panel is used

[Ville Syrjälä]

On Mon, Mar 22, 2021 at 10:28:06PM +0100, Hans de Goede wrote:
> Hi,
> 
> On 3/22/21 9:59 PM, Ville Syrjälä wrote:
> > On Mon, Mar 22, 2021 at 04:51:47PM -0400, Rodrigo Vivi wrote:
> >> On Fri, Mar 19, 2021 at 04:45:32PM +0100, Hans de Goede wrote:
> >>> Hi,
> >>>
> >>> On 3/1/21 4:43 PM, Hans de Goede wrote:
> >>>> After the recently added commit fe0f1e3bfdfe ("drm/i915: Shut down
> >>>> displays gracefully on reboot"), the DSI panel on a Cherry Trail based
> >>>> Predia Basic tablet would no longer properly light up after reboot.
> >>>>
> >>>> The backlight still turns back on after reboot, but the LCD shows an
> >>>> all black display. The display is also all black during the time that
> >>>> EFI / the GOP is managing it, so e.g. the grub menu also is not visible.
> >>>>
> >>>> In this scenario the panel is initialized so that it appears to be working
> >>>> and the fastboot code skips doing a modeset. Forcing a modeset by doing a
> >>>> chvt to a text-console over ssh followed by echo-ing 1 and then 0 to
> >>>> /sys/class/graphics/fb0/blank causes the panel to work again.
> >>>>
> >>>> Add a QUIRK_SKIP_SHUTDOWN quirk which turns i915_driver_shutdown() into
> >>>> a no-op when set; and set this on vlv/chv devices when a DSI panel is
> >>>> detected, to work around this.
> >>>>
> >>>> Admittedly this is a bit of a big hammer, but these platforms have been
> >>>> around for quite some time now and they have always worked fine without
> >>>> the new behavior to shutdown everything on shutdown/reboot. This approach
> >>>> simply disables the recently introduced new shutdown behavior in this
> >>>> specific case where it is known to cause problems. Which is a nice and
> >>>> simple way to deal with this.
> >>>>
> >>>> Signed-off-by: Hans de Goede <hdegoede at redhat.com>
> >>>
> >>> Ping? Since sending this patch I've been seeing the issue addressed by
> >>> this on variour other CHT based devices too.
> >>>
> >>> So we have various devices suffering from a black screen after reboot
> >>> now. This is pretty serious usability regression.
> >>>
> >>> As such it would be good to get this reviewed, or another fix proposed.
> >>
> >> For the quirks we try to limit them to very specific vendor and model ids,
> >> so I wonder if it would be possible to get this information in here instead
> >> to all the vlv with dsi...
> >>
> >> Or avoid the quirk "infra" and skip to all vlv with active dsi?!
> >>
> >> Jani?
> >> Ville?
> > 
> > We need to figure out why the panel doesn't start up again.
> 
> Note it is the GOP which fails to light it up again. I think we turn something
> off, which after a power-on-reset is on, so the GOP expects it to be on.

Hmm. Do any of the reboot=warm|cold|whatever knobs make a difference?
Are there any fast vs. slow boot settings in the BIOS setup?

-- 
Ville Syrjälä
Intel