Re: [Intel-gfx] [PATCH] drm/i915: Officially give up on seqno coherency

From: Jani Nikula <jani.nikula@linux.intel.com>
To: Intel Graphics Development <intel-gfx@lists.freedesktop.org>
Cc: Daniel Vetter <daniel.vetter@intel.com>,
	Daniel Vetter <daniel.vetter@ffwll.ch>,
	stable@vger.kernel.org
Subject: Re: [Intel-gfx] [PATCH] drm/i915: Officially give up on seqno coherency
Date: Tue, 23 Jun 2015 13:05:41 +0300	[thread overview]
Message-ID: <87381i20zu.fsf@intel.com> (raw)
In-Reply-To: <1434741369-28932-1-git-send-email-daniel.vetter@ffwll.ch>

On Fri, 19 Jun 2015, Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
> We've never figured out the magic trick to make irq vs. seqno
> updates coherent, only tricks to make it work. And since
>
> commit 094f9a54e35500739da185cdb78f2e92fc379458
> Author: Chris Wilson <chris@chris-wilson.co.uk>
> Date:   Wed Sep 25 17:34:55 2013 +0100
>
>     drm/i915: Fix __wait_seqno to use true infinite timeouts
>
> we automatically fall back to an irq augmented with polling scheme
> after the first missed interrupt. There's really nothing else we can
> do, hence tune down the message to informational level. It's still
> useful for users in case it reliable preceedes a hard system hang.
>
> v2: Use NOTICE since it might be of value for bug reports (Chris).
>
> Cc: Mark Janes <mark.a.janes@intel.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: stable@vger.kernel.org
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_irq.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index e6bb72dca3ff..5072fb49367e 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -2946,8 +2946,8 @@ static void i915_hangcheck_elapsed(struct work_struct *work)
>  					/* Issue a wake-up to catch stuck h/w. */
>  					if (!test_and_set_bit(ring->id, &dev_priv->gpu_error.missed_irq_rings)) {
>  						if (!(dev_priv->gpu_error.test_irq_rings & intel_ring_flag(ring)))
> -							DRM_ERROR("Hangcheck timer elapsed... %s idle\n",
> -								  ring->name);
> +							DRM_NOTICE("Hangcheck timer elapsed... %s idle\n",

drivers/gpu/drm/i915/i915_irq.c: In function ‘i915_hangcheck_elapsed’:
drivers/gpu/drm/i915/i915_irq.c:2949:8: error: implicit declaration of function ‘DRM_NOTICE’ [-Werror=implicit-function-declaration]
        DRM_NOTICE("Hangcheck timer elapsed... %s idle\n",
        ^

BR,
Jani.

> +								   ring->name);
>  						else
>  							DRM_INFO("Fake missed irq on %s\n",
>  								 ring->name);
> -- 
> 2.1.4
>
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-- 
Jani Nikula, Intel Open Source Technology Center