[Intel-gfx] [PATCH v4] drm/i915: Avoid GPU Hang when comming out of s3 or s4

[Greg KH]

On Mon, May 11, 2015 at 12:05:27PM +0100, Peter Antoine wrote:
> This patch fixed a timing issue that causes a GPU hang when a the system
> comes out of power saving.
> 
> During pm_resume, We are submitting batchbuffers before enabling
> Interrupts this is causing us to miss the context switch interrupt,
> and in consequence intel_execlists_handle_ctx_events is not triggered.
> 
> This patch is based on a patch from Deepak S <deepak.s at intel.com>
> from another platform.
> 
> The patch fixes an issue introduced by:
>   commit e7778be1eab918274f79603d7c17b3ec8be77386
>   drm/i915: Fix startup failure in LRC mode after recent init changes
> 
> The above patch added a call to init_context() to fix an issue introduced
> by a previous patch. But, it then opened up a small timing window for the
> batches being added by the init_context (basically setting up the context)
> to complete before the interrupts have been turned on, thus hanging the
> GPU.
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=89600
> Signed-off-by: Peter Antoine <peter.antoine at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read Documentation/stable_kernel_rules.txt
for how to do this properly.

</formletter>