[Intel-gfx] [PATCH 08/11] drm/i915: don't write 0 to DIP control at HDMI init

[Jesse Barnes]

On Thu, 24 May 2012 17:49:50 -0300
Paulo Zanoni <przanoni at gmail.com> wrote:

> From: Paulo Zanoni <paulo.r.zanoni at intel.com>
> 
> At this time, the HDMI port is enabled, and the DIP control register
> specification says we need to disable the port *before* disabling the
> DIPs. Also, while doing this we risk telling the HW to send the AVI
> DIPs once (not every VSync), which really seems to confuse the HW and
> trigger bugs where the DIPs are not sent.
> 
> This code was here just to set the DIP register to a 'known state'
> before using it, but since now the set_infoframes functions already
> set the control registers to a known state, this code can go away.
> 
> Also, the previous code disables *all* the DIP registers for *each*
> HDMI port, so we end disabling each DIP register more than once.
> 
> This patch solves a problem I can reproduce on my IVB machine. When I
> boot it with just a single HDMI monitor, the AVI InfoFrames are not
> sent. With this patch, the InfoFrames are sent. Previously, I wrote a
> patch to 'touch the DIP registers after we enable the HDMI port' to
> solve this same problem, but that patch doesn't seem to be needed
> anymore after this patch.
> 
> All this patch does is revert a chunk of the following commit:
> 
>     commit 64a8fc0145a1d0fdc25fc9367c2e6c621955fb3b
>     Author: Jesse Barnes <jbarnes at virtuousgeek.org>
>     Date:   Thu Sep 22 11:16:00 2011 +0530
> 
>         drm/i915: fix ILK+ infoframe support
> 
> So bugs that can be bisected to that commit may be fixed now.
> 
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=43256
> Cc: jbarnes at virtuousgeek.org
> Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>

Acked-by: Jesse Barnes <jbarnes at virtuousgeek.org>

Thanks for tracking down the right disable and enable order on all the
generations Paulo! \o/

-- 
Jesse Barnes, Intel Open Source Technology Center