linux-kernel - Re: [PATCH] drm/i915: Suppress spurious vblank interrupts

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Message-ID: <alpine.LSU.2.00.1106172136290.21481@sister.anvils>
Date:	Fri, 17 Jun 2011 21:40:15 -0700 (PDT)
From:	Hugh Dickins <hughd@...gle.com>
To:	Chris Wilson <chris@...is-wilson.co.uk>
cc:	Mario Kleiner <mario.kleiner@...bingen.mpg.de>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/i915: Suppress spurious vblank interrupts

On Mon, 14 Feb 2011, Hugh Dickins wrote:
> On Fri, Feb 11, 2011 at 10:21 AM, Mario Kleiner
> <mario.kleiner@...bingen.mpg.de> wrote:
> > On Feb 8, 2011, at 8:52 PM, Hugh Dickins wrote:
> >>  It appears that the
> >> underruns, while mysterious and worrisome, have litte or nothing to do
> >> with the unflushed text problem which is making 2.6.38-rc unusable.
> >>
> I'm sorry to say that I have now given up on this: it has already
> consumed a lot more time than I can afford to give it.  So I've now
> just turned CONFIG_DRM_I915_KMS off, which gives me a laptop on which
> 2.6.38-rc is usable.
> 
> If in due course there's a likely patch someone would like me to try,
> that I can do.  And from time to time, with new kernels and with
> upgraded userspace, I'll give I915_KMS a try again - indeed, for the
> moment I still have it in my 64bit kernel.
> 
> Before switching KMS off, I did establish that, with Chris's overrun
> fix, do_intel_finish_page_flip() - the function whose call to
> do_gettimeofday() I moved - is no longer called at all.  So that
> modification was just cargo-cult magic by now (though perhaps made a
> difference to timings when overruns were happening), and there's no
> reason to suspect Mario's vblank patch at all.  Let's assume that if I
> attempted a fifth bisection, it would lead me to another (equally
> blameless) patch.  Nobody else is complaining: maybe my 965 is broken
> and just gets along better with 2.6.38 KMS off.

Just wanted to report that something (sorry, no time to work out what)
in 3.0-rc1 fixed this issue for me, so now I am back on I915_KMS: thanks.

Hugh