[PATCH v2] drm: Only create a cmdline mode if no probed modes match
chris at chris-wilson.co.uk
Thu May 21 08:36:41 PDT 2015
On Mon, Apr 20, 2015 at 03:41:48PM +0200, Radek Dostál wrote:
> On 04/20/2015 03:28 PM, Chris Wilson wrote:
> > The intention of using video=<connector>:<mode> is primarily to select
> > the user's preferred resolution at startup. Currently we always create a
> > new mode irrespective of whether the monitor has a native mode at the
> > desired resolution. This has the issue that we may then select the fake
> > mode rather the native mode during fb_helper->inital_config() and so
> > if the fake mode is invalid we then end up with a loss of signal. Oops.
> > This invalid fake mode would also be exported to userspace, who
> > potentially may make the same mistake.
> > To avoid this issue, we filter out the added command line mode if we
> > detect the desired resolution (and clock if specified) amongst the
> > probed modes. This fixes the immediate problem of adding a duplicate
> > mode, but perhaps more generically we should avoid adding a GTF mode if
> > the monitor has an EDID that is not GTF-compatible, or similarly for
> > CVT.
> > A second issue sneaked into this patch is to add the cmdline mode mode
> > ahead of the absolute fallback 1024x768 mode. That is if the user has
> > specified a mode that we create as a fallback, we do not need to add a
> > second unused fallback mode.
> > Fixes regression from
> > commit eaf99c749d43ae74ac7ffece5512f3c73f01dfd2
> > Author: Chris Wilson <chris at chris-wilson.co.uk>
> > Date: Wed Aug 6 10:08:32 2014 +0200
> > drm: Perform cmdline mode parsing during connector initialisation
> > that breaks HDMI output on BeagleBone Black with LG TV (model 19LS4R-ZA).
> > v2: Explicitly delete our earlier cmdline mode
> > Reported-by: Radek Dostál <rd at radekdostal.com>
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Radek Dostál <rd at radekdostal.com>
> > Cc: Jesse Barnes <jbarnes at virtuousgeek.org>
> > Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> > Cc: dri-devel at lists.freedesktop.org
> > Cc: Julia Lemire <jlemire at matrox.com>
> > Cc: Dave Airlie <airlied at redhat.com>
> > Cc: stable at vger.kernel.org
> works now :)
> Tested-by: Radek Dostál <rd at radekdostal.com>
Daniel, Dave do either or you want to pick this up for your fixes tree?
Chris Wilson, Intel Open Source Technology Centre
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