[PATCH] drm/gma500: Add CedarView LVDS blacklist

[Patrik Jakobsson]

On Wed, Apr 10, 2019 at 1:51 PM Dominik 'Rathann' Mierzejewski
<dominik at greysector.net> wrote:
>
> On Wednesday, 10 April 2019 at 13:33, Patrik Jakobsson wrote:
> > On Wed, Apr 10, 2019 at 1:18 PM Dominik 'Rathann' Mierzejewski
> > <dominik at greysector.net> wrote:
> > >
> > > On Wednesday, 10 April 2019 at 11:08, Hans de Goede wrote:
> > > > On 10-04-19 11:00, Patrik Jakobsson wrote:
> > > > > On Wed, Apr 10, 2019 at 9:27 AM Hans de Goede <hdegoede at redhat.com> wrote:
> > > > > > On 09-04-19 21:31, Dominik 'Rathann' Mierzejewski wrote:
> > > > > > > On Tuesday, 09 April 2019 at 16:44, Hans de Goede wrote:
> > > > > > > > On 09-04-19 14:05, Patrik Jakobsson wrote:
> > > [...]
> > > > > > > > > I'm not totally against this but not sure about the consequences. Is
> > > > > > > > > there perhaps a better dmi string to match against?
> > > > > > > >
> > > > > > > > No there are no better DMI strings to match against I'm afraid.
> > > > > > >
> > > > > > > I did load default settings in BIOS setup and there's no change in
> > > > > > > behaviour. LVDS gets detected as connected:
> > > > > > > $ cat /sys/class/drm/card0-LVDS-1/status
> > > > > > > connected
> > > > > > >
> > > > > > > Only VGA output is physically connected at the moment.
> > > > > >
> > > > > > To be clear what Dominik means here is that he has a VGA monitor
> > > > > > connected. There is no LVDS panel in this device at all.
> > > > >
> > > > > Thanks for testing. I dusted off my DN2800MT and tried turning LVDS
> > > > > on/off in the BIOS. With LVDS disabled gma500 reports it as connected.
> > > > > When LVDS is enabled in bios I instead get a connected eDP connector.
> > > > > I'm starting to think that broken VBT parsing might be the actual
> > > > > problem.
> > > >
> > > > Maybe, but I assume there are CedarView based laptops with LVDS panels
> > > > which works, so I suspect this might be more of a bug in your BIOS.
> > > >
> > > > So what is the next step in debugging this?
> > >
> > > To add a small twist, I got an updated BIOS from the vendor to fix
> > > another issue (https://bugzilla.kernel.org/show_bug.cgi?id=199117)
> > > and the DMI string has changed to: "CDV W Series 05", so Hans' patch
> > > no longer matches my machine.
> >
> > Hi Dominik,
> >
> > Do you have any option to enable/disable LVDS in your BIOS. The BIOS
> > default might not be to disable LVDS since they apparently solved the
> > issue on the command line anyway. If there is an option to turn it off
> > but you still get the same problem, then it is possible that detection
> > of "LVDS disabled" in the driver might be bad.
>
> No, there's no option to enable/disable LVDS. The machine is a NAS box
> and doesn't have an LVDS physically. You can see the motherboard e.g.
> here: https://youtu.be/ZYNQvZNGLsE?t=855 .

I've posted a patch: https://patchwork.freedesktop.org/patch/299821/

Previously we only checked for a child device and ignored the lvds
config bits. Hopefully this fixes your problem.

-Patrik

>
> Regards,
> Dominik
> --
> Fedora   https://getfedora.org  |  RPM Fusion  http://rpmfusion.org
> There should be a science of discontent. People need hard times and
> oppression to develop psychic muscles.
>         -- from "Collected Sayings of Muad'Dib" by the Princess Irulan