[Intel-gfx] [PATCH] drm/i915: preserve dispaly init order on ByT

Artem Bityutskiy artem.bityutskiy at linux.intel.com
Thu Oct 17 16:03:01 CEST 2013

On Wed, 2013-10-16 at 19:46 +0200, Daniel Vetter wrote:
> On Wed, Oct 16, 2013 at 06:10:41PM +0300, Artem Bityutskiy wrote:
> > From: Artem Bityutskiy <artem.bityutskiy at linux.intel.com>
> > 
> > This patch changes HDMI port registration order for the BayTrail platform.
> > 
> > The story is that in kernel version 3.11 i915 supported only one HDMI port -
> > the HDMIB port. So this port ended up being HDMI-1 in user-space.
> > 
> > But commit '6f6005a drm/i915: expose HDMI connectors on port C on BYT'
> > introduced HDMIC port support. And added HDMIC  registration prior to HDMIB,
> > so HDMIB became HDMI-2 and HDMIC became HDMI-1.
> > 
> > Well, this is fine as far as the kernel is concerned. i915 does not give any
> > guarantees to the numbering, and has never given them.
> > 
> > However, this breaks wayland setup in Tizen IVI. We have only one single HDMI
> > port on our hardware, and it is connected to HDMIB. Our configuration relies on
> > the fact that it is HDMI-1.
> > 
> > Well, certainly this is user-space problem which was exposed with Jesse's
> > patch. However, there is a reason why we have to do this assumption - we use
> > touchscreen monitors and we have to associate event devices with the monitors,
> > and this is not easy to do dynamically, so we just have a static setup.
> > 
> > Anyway, while the user-space setup will have to be fixed regardless, let's
> > chane the HDMI port registration order so that HDMIB stays HDMI-1, just like it
> > was in 3.11. Simply because there is no strong reason for changing the order in
> > the kernel, and it'll help setups like ours in sense that we'll have more time
> > for fixing the issue properly.
> > 
> > Also amend the commentary which looks a bit out-of-date.
> > 
> > Signed-off-by: Artem Bityutskiy <artem.bityutskiy at linux.intel.com>
> This makes imo sense irrespective of any userspace issues. Queued for
> -next, thanks for the patch.
> -Daniel

Thanks Daniel! Although, '6f6005a drm/i915: expose HDMI connectors on
port C on BYT' is in 3.12-rc4, is it possible to have this patch in 3.12
release too?

Best Regards,
Artem Bityutskiy

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