[Intel-gfx] [PATCH] drm/i915: Read the hardware state for the transcoder link upon error

[Chris Wilson]

On Mon, Jun 24, 2013 at 09:59:33AM +0200, Daniel Vetter wrote:
> On Fri, Jun 21, 2013 at 03:40:04PM +0100, Chris Wilson wrote:
> > Do not trust our bookkeeping when reporting errors, and instead dump the
> > register contents. In particular, this solves one particular issue when
> > an error is reported before we finish setting up the outputs and have a
> > complete mapping (i.e. during initialisation we set garbage state). If
> > an error occurs at that early stage, it is vital that we get an accurate
> > report of the hardware state and not conflated with our own inaccurate
> > opinions.
> > 
> > This fixes a panic for a large number of pre-Haswell machines that
> > currently trigger an error during KMS takeover.
> > 
> > Reported-by: Dustin King <daking at rescomp.stanford.edu>
> > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=60021
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: stable at vger.kernel.org
> 
> Shouldn't we just dump all transcoder registers on Haswell instead of
> potentially fragile dances trying to reconstruct state?

You still need to reconstruct the pipe->transcoder link as they are
separate banks of registers. This patch is just a smaller part of the
patch to dump everything.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre