Re: [PATCH] drm/gma500: Add CedarView LVDS blacklist

From: Dominik 'Rathann' Mierzejewski <dominik@greysector.net>
To: Hans de Goede <hdegoede@redhat.com>
Cc: David Airlie <airlied@linux.ie>,
	Daniel Vetter <daniel.vetter@intel.com>,
	dri-devel <dri-devel@lists.freedesktop.org>
Subject: Re: [PATCH] drm/gma500: Add CedarView LVDS blacklist
Date: Wed, 10 Apr 2019 13:18:29 +0200	[thread overview]
Message-ID: <20190410111829.GC3178@sakura.greysector.net> (raw)
In-Reply-To: <82afbb86-433a-a0ba-e06f-8badd5862943@redhat.com>

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@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.

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
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