Re: drm/i915 4.5/4.6 stable backport request for CHV

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Sat, Jun 04, 2016 at 02:06:58PM -0700, Greg KH wrote:
> On Fri, May 27, 2016 at 11:30:30AM +0300, ville.syrjala@linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > Several nasty i915 regressions affecting CHV slipped through
> > to 4.5 and 4.6.
> > 
> > The first fix we want in 4.5 and 4.6 is
> > commit caed361d83b2 ("drm/i915: Fix watermarks for VLV/CHV")
> > It won't cherry-pick cleanly to either one, so I've included conflict
> > free versions for both. This one fixes display FIFO underruns that can
> > lead to the screen totally blanking out.
> 
> Now applied, thanks.
> 
> > The other one I'd like to have in 4.6 is
> > commit 9f6151c90390 ("drm/i915: Pass the correct crtc state to .update_plane()")
> > which avoids a totally corrupted display in some cases.
> 
> Now applied.
> 
> > And the third on is a bit more annoying. The regression is caused by
> > commit 9dbaab56ac09 ("drm/i915: Exit cherryview_irq_handler() after one pass")
> > which I though we had prevented from getting out on its own, but turns
> > out I was wrong. It basically makes the GPU unusable, so we do need to
> > fix it somehow. The simple solution would be to revert it in 4.6 only.
> > The more complicated solution is to backport the proper fix, which more
> > or less requires the following set of commits [1], which is maybe a bit
> > too much for stable. I could try to trim it a bit perhaps, but then we
> > start to enter the territory of untested code which I don't particularly
> > like. Let me know what you think.
> > 
> > [1]
> >  1e1cace942ef ("drm/i915: Eliminate loop from VLV irq handler")
> >  a5e485a95c9c ("drm/i915: Clear VLV_IER around irq processing")
> >  4a0a0202b023 ("drm/i915: Clear VLV_MASTER_IER around irq processing")
> >  7ce4d1f2730f ("drm/i915: Clear VLV_IIR after PIPESTAT")
> >  34c7b8a7b8b5 ("drm/i915: Set up VLV_MASTER_IER consistently")
> >  e5328c43d46e ("drm/i915: Use GEN8_MASTER_IRQ_CONTROL consistently")
> >  71b8b41d5b35 ("drm/i915: Move DPINVGTT setup to vlv_display_irq_reset()")
> >  6b7eafc1b43d ("drm/i915: Warn if irq_mask isn't ~0 during vlv/cvh display irq postinstall")
> >  9ab981f22bef ("drm/i915: Use GEN5_IRQ_INIT() in vlv_display_irq_postinstall()")
> >  d6c698035892 ("drm/i915: Clear display interrupt before enabling when turning on the power well")
> >  8bb613068a63 ("drm/i915: Move vlv/chv display irq code to a more logical place")
> >  9918271efc7a ("drm/i915: Skip display irq setup if display irqs aren't flagged as enabled")
> >  ad22d10654ea ("drm/i915: Fix up vlv/chv display irq setup")
> >  93de68f94081 ("drm/i915: Remove "VLV magic" from irq setup")
> 
> I think reverting that one patch for 4.6 makes more sense than adding
> all of these patches.  I'll do that if you want me to.

That works for me. Thanks.

-- 
Ville Syrjälä
Intel OTC