On 16/02/15 16:12, Thomas Daniel wrote:
> Work was getting left behind in LRC contexts during reset. This causes a hang
> if the GPU is reset when HEAD==TAIL because the context's ringbuffer head and
> tail don't get reset and retiring a request doesn't alter them, so the ring
> still appears full.
>
> Added a function intel_lr_context_reset() to reset head and tail on a LRC and
> its ringbuffer.
>
> Call intel_lr_context_reset() for each context in i915_gem_context_reset()
> when
> in execlists mode.
>
> Testcase: igt/pm_rps --run-subtest reset #bdw
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=88096
> Signed-off-by: Thomas Daniel <thomas.dan...@intel.com>
> ---
> drivers/gpu/drm/i915/i915_gem_context.c | 12 +++++++----
> drivers/gpu/drm/i915/intel_lrc.c | 34
> +++++++++++++++++++++++++++++++
> drivers/gpu/drm/i915/intel_lrc.h | 2 ++
> 3 files changed, 44 insertions(+), 4 deletions(-)
A couple of minor points below, but not ones that require changes, so:
Reviewed-by: Dave Gordon <david.s.gor...@intel.com>
> diff --git a/drivers/gpu/drm/i915/i915_gem_context.c
> b/drivers/gpu/drm/i915/i915_gem_context.c
> index 8603bf4..70346b0 100644
> --- a/drivers/gpu/drm/i915/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/i915_gem_context.c
> @@ -296,11 +296,15 @@ void i915_gem_context_reset(struct drm_device *dev)
> struct drm_i915_private *dev_priv = dev->dev_private;
> int i;
>
> - /* In execlists mode we will unreference the context when the execlist
> - * queue is cleared and the requests destroyed.
> - */
> - if (i915.enable_execlists)
> + if (i915.enable_execlists) {
> + struct intel_context *ctx;
> +
> + list_for_each_entry(ctx, &dev_priv->context_list, link) {
> + intel_lr_context_reset(dev, ctx);
> + }
> +
> return;
> + }
>
> for (i = 0; i < I915_NUM_RINGS; i++) {
> struct intel_engine_cs *ring = &dev_priv->ring[i];
> diff --git a/drivers/gpu/drm/i915/intel_lrc.c
> b/drivers/gpu/drm/i915/intel_lrc.c
> index aafcef3..1946bb9 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/intel_lrc.c
> @@ -1950,3 +1950,37 @@ error_unpin_ctx:
> drm_gem_object_unreference(&ctx_obj->base);
> return ret;
> }
> +
> +void intel_lr_context_reset(struct drm_device *dev,
> + struct intel_context *ctx)
> +{
> + struct drm_i915_private *dev_priv = dev->dev_private;
> + struct intel_engine_cs *ring;
> + int i;
> +
> + for_each_ring(ring, dev_priv, i) {
> + struct drm_i915_gem_object *ctx_obj =
> + ctx->engine[ring->id].state;
> + if (ctx_obj) {
> + struct intel_ringbuffer *ringbuf =
> + ctx->engine[ring->id].ringbuf;
> + uint32_t *reg_state;
> + struct page *page;
> +
> + if (i915_gem_object_get_pages(ctx_obj)) {
> + WARN(1, "Failed get_pages for context obj\n");
> + continue;
> + }
This could be folded into a single "if (WARN_ON(...)) continue;"
> + page = i915_gem_object_get_page(ctx_obj, 1);
Isn't it a pity that we have i915_gem_object_get_page() and
i915_gem_object_get_pages() which look so similar but do completely
different things :(
> + reg_state = kmap_atomic(page);
> +
> + reg_state[CTX_RING_HEAD+1] = 0;
> + reg_state[CTX_RING_TAIL+1] = 0;
> +
> + kunmap_atomic(reg_state);
> +
> + ringbuf->head = 0;
> + ringbuf->tail = 0;
> + }
> + }
> +}
> diff --git a/drivers/gpu/drm/i915/intel_lrc.h
> b/drivers/gpu/drm/i915/intel_lrc.h
> index f635735..5dd0eca 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.h
> +++ b/drivers/gpu/drm/i915/intel_lrc.h
> @@ -73,6 +73,8 @@ int intel_lr_context_deferred_create(struct intel_context
> *ctx,
> struct intel_engine_cs *ring);
> void intel_lr_context_unpin(struct intel_engine_cs *ring,
> struct intel_context *ctx);
> +void intel_lr_context_reset(struct drm_device *dev,
> + struct intel_context *ctx);
>
> /* Execlists */
> int intel_sanitize_enable_execlists(struct drm_device *dev, int
> enable_execlists);
>
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