[Intel-gfx] [PATCH] drm/i915: Reset CSB read pointer when enabling contexts

[Daniel Vetter]

On Wed, Jan 07, 2015 at 04:09:30PM +0000, Thomas Daniel wrote:
> During a suspend/resume cycle the hardware Context Status Buffer write pointer
> is reset.  However since recent changes to the init sequence the software CSB
> read pointer is no longer reset.  This means that context status events are not
> handled correctly and new contexts are not written to the ELSP, resulting in an
> apparent GPU hang.
> 
> Pending further changes to the ring init code, just move the
> ring->next_context_status_buffer initialization into i915_gem_context_enable to
> fix this regression.
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=88097
There's also

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=88096

Can you please take a look at that one too?
-Daniel

> Cc: Paulo Zanoni <paulo.r.zanoni at intel.com>
> Signed-off-by: Thomas Daniel <thomas.daniel at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_gem_context.c |    1 +
>  drivers/gpu/drm/i915/intel_lrc.c        |    1 -
>  2 files changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
> index bf9778e..cc100c9 100644
> --- a/drivers/gpu/drm/i915/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/i915_gem_context.c
> @@ -412,6 +412,7 @@ int i915_gem_context_enable(struct drm_i915_private *dev_priv)
>  
>  	if (i915.enable_execlists) {
>  		for_each_ring(ring, dev_priv, i) {
> +			ring->next_context_status_buffer = 0;
>  			if (ring->init_context) {
>  				ret = ring->init_context(ring,
>  						ring->default_context);
> diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
> index 7670a0f..4580267 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/intel_lrc.c
> @@ -1394,7 +1394,6 @@ static int logical_ring_init(struct drm_device *dev, struct intel_engine_cs *rin
>  	INIT_LIST_HEAD(&ring->execlist_queue);
>  	INIT_LIST_HEAD(&ring->execlist_retired_req_list);
>  	spin_lock_init(&ring->execlist_lock);
> -	ring->next_context_status_buffer = 0;
>  
>  	ret = i915_cmd_parser_init_ring(ring);
>  	if (ret)
> -- 
> 1.7.9.5
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch