[Intel-gfx] [PATCH 05/17] drm/i915/tv: Clear state sense detection for Cantiga

[Eric Anholt]

On Thu, 21 Apr 2011 22:18:20 +0100, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> From: Zhao Yakui <yakui.zhao at intel.com>
> 
> ... otherwise the TV type will be misdetected and cause spurious
> connections.
> 
> This was originally applied as fb8b5a39b6310379d7b54c0c7113703a8eaf4a57
> (drm/i915: Configure the TV sense state correctly on GM45 to make TV
> detection reliable)
> 
> Eric: Shortly after applying this patch you requested it to be reverted,
> d4b74bf07873da2e94219a7b67a334fc1c3ce649 (Revert "drm/i915: Configure
> the TV sense state correctly on GM45 to make TV), but we have no clear
> information just what is broken by this patch and how to resolve it.

The patch, as explained at the time, basically said "TV detection is
unreliable", and the contents of the patch looked like it was turning
off the detection by disabling TVDAC_STATE_CHG_EN.  The tester said that
it successfully made his TV appear disconnected.  Thus it looked to me
like a patch that was just disabling TV detection on this platform in a
roundabout way, and because of that I hadn't meant to send it upstream.

Maybe it actually makes things work (both for not-detecting no TV, and
detecting a real TV).  But I also didn't like the "because HW
requirement", instead of some specific explanation (some reason why we
need low sense level on the channels instead of high, and some reason to
disable tvdac_state_chg_en at the same time) or a pointer at some docs.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 197 bytes
Desc: not available
URL: <http://lists.freedesktop.org/archives/intel-gfx/attachments/20110421/a6754f7d/attachment.sig>