drm/i915: Remove request->reset_counter

Since commit 2ed53a94d8cb ("drm/i915: On GPU reset, set the HWS
breadcrumb to the last seqno") once a hang is completed, the seqno is
advanced past all current requests. With this we know that if we wake up
from waiting for a request, if a hang has occurred and reset completed,
our request will be considered complete (i.e.
i915_gem_request_completed() returns true). Therefore we only need to
worry about the situation where a hang has occurred, but not yet reset,
where we may need to release our struct_mutex. Since we don't need to
detect the completed reset using the global gpu_error->reset_counter
anymore, we do not need to track the reset_counter epoch inside the
request.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Arun Siluvery <arun.siluvery@linux.intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1467211874-11552-1-git-send-email-chris@chris-wilson.co.uk
Reviewed-by: Arun Siluvery <arun.siluvery@linux.intel.com>

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 724d34b..82b20e1 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2368,7 +2368,6 @@ struct drm_i915_gem_request {
        /** On Which ring this request was generated */
        struct drm_i915_private *i915;
        struct intel_engine_cs *engine;
-       unsigned reset_counter;
 
         /** GEM sequence number associated with the previous request,
          * when the HWS breadcrumb is equal to this the GPU is processing

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 51191b8..1d98782 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1506,12 +1506,13 @@ int __i915_wait_request(struct drm_i915_gem_request *req,
 
                /* We need to check whether any gpu reset happened in between
                 * the request being submitted and now. If a reset has occurred,
-                * the request is effectively complete (we either are in the
-                * process of or have discarded the rendering and completely
-                * reset the GPU. The results of the request are lost and we
-                * are free to continue on with the original operation.
+                * the seqno will have been advance past ours and our request
+                * is complete. If we are in the process of handling a reset,
+                * the request is effectively complete as the rendering will
+                * be discarded, but we need to return in order to drop the
+                * struct_mutex.
                 */
-               if (req->reset_counter != i915_reset_counter(&dev_priv->gpu_error)) {
+               if (i915_reset_in_progress(&dev_priv->gpu_error)) {
                        ret = 0;
                        break;
                }
@@ -1685,7 +1686,7 @@ i915_wait_request(struct drm_i915_gem_request *req)
                return ret;
 
        /* If the GPU hung, we want to keep the requests to find the guilty. */
-       if (req->reset_counter == i915_reset_counter(&dev_priv->gpu_error))
+       if (!i915_reset_in_progress(&dev_priv->gpu_error))
                __i915_gem_request_retire__upto(req);
 
        return 0;
@@ -1746,7 +1747,7 @@ i915_gem_object_retire_request(struct drm_i915_gem_object *obj,
        else if (obj->last_write_req == req)
                i915_gem_object_retire__write(obj);
 
-       if (req->reset_counter == i915_reset_counter(&req->i915->gpu_error))
+       if (!i915_reset_in_progress(&req->i915->gpu_error))
                __i915_gem_request_retire__upto(req);
 }
 
@@ -3021,7 +3022,6 @@ __i915_gem_request_alloc(struct intel_engine_cs *engine,
        kref_init(&req->ref);
        req->i915 = dev_priv;
        req->engine = engine;
-       req->reset_counter = reset_counter;
        req->ctx  = ctx;
        i915_gem_context_reference(req->ctx);