drm/i915: Treat kernel context as initialised

The kernel context exists simply as a placeholder and should never be
executed with a render context. It does not need the golden render
state, as that will always be applied to a user context. By skipping the
initialisation we can avoid issues in attempting to program the golden
render context when trying to make the hardware idle.

v2: Rebase

Testcase: igt/drm_module_reload_basic #byt
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=95634
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1466776558-21516-3-git-send-email-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 419d255..4f4fd65 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -472,13 +472,17 @@ void i915_gem_context_lost(struct drm_i915_private *dev_priv)
                        i915_gem_context_unpin(engine->last_context, engine);
                        engine->last_context = NULL;
                }
-
-               /* Force the GPU state to be reinitialised on enabling */
-               dev_priv->kernel_context->engine[engine->id].initialised =
-                       engine->init_context == NULL;
        }
 
-       /* Force the GPU state to be reinitialised on enabling */
+       /* Force the GPU state to be restored on enabling */
+       if (!i915.enable_execlists) {
+               for_each_engine(engine, dev_priv) {
+                       struct intel_context *kce =
+                               &dev_priv->kernel_context->engine[engine->id];
+
+                       kce->initialised = true;
+               }
+       }
        dev_priv->kernel_context->remap_slice = ALL_L3_SLICES(dev_priv);
 }
 

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 86b80b4..04a2d14 100644 (file)
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -2338,6 +2338,16 @@ static int intel_ring_context_pin(struct i915_gem_context *ctx,
                        goto error;
        }
 
+       /* The kernel context is only used as a placeholder for flushing the
+        * active context. It is never used for submitting user rendering and
+        * as such never requires the golden render context, and so we can skip
+        * emitting it when we switch to the kernel context. This is required
+        * as during eviction we cannot allocate and pin the renderstate in
+        * order to initialise the context.
+        */
+       if (ctx == ctx->i915->kernel_context)
+               ce->initialised = true;
+
        i915_gem_context_reference(ctx);
        return 0;