[PATCH] drm/i915/bdw: Render moot context reset and switch with Execlists

Thomas Daniel
2014-08-20T15:29:28Z

These two functions make no sense in an Logical Ring Context & Execlists
world.

v2: We got rid of lrc_enabled and centralized everything in the sanitized
i915.enable_execlists instead.

Signed-off-by: Oscar Mateo <oscar.mateo@intel.com>

v3: Rebased. Corrected a typo in comment for i915_switch_context and
added a comment that it should not be called in execlist mode. Added
WARN_ON if i915_switch_context is called in execlist mode. Moved check
for execlist mode out of i915_switch_context and into callers. Added
comment in context_reset explaining why nothing is done in execlist
mode.

Signed-off-by: Thomas Daniel <thomas.daniel@intel.com>
---
drivers/gpu/drm/i915/i915_gem.c | 8 +++++---
drivers/gpu/drm/i915/i915_gem_context.c | 16 +++++++++++++++-
2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index cb9310b..954a5f9 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2981,9 +2981,11 @@ int i915_gpu_idle(struct drm_device *dev)

/* Flush everything onto the inactive list. */
for_each_ring(ring, dev_priv, i) {
- ret = i915_switch_context(ring, ring->default_context);
- if (ret)
- return ret;
+ if (!i915.enable_execlists) {
+ ret = i915_switch_context(ring, ring->default_context);
+ if (ret)
+ return ret;
+ }

ret = intel_ring_idle(ring);
if (ret)
diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 0fdb357..3face51 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -289,6 +289,12 @@ 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)
+ return;
+
for (i = 0; i < I915_NUM_RINGS; i++) {
struct intel_engine_cs *ring = &dev_priv->ring[i];
struct intel_context *lctx = ring->last_context;
@@ -397,6 +403,9 @@ int i915_gem_context_enable(struct drm_i915_private *dev_priv)

BUG_ON(!dev_priv->ring[RCS].default_context);

+ if (i915.enable_execlists)
+ return 0;
+
for_each_ring(ring, dev_priv, i) {
ret = i915_switch_context(ring, ring->default_context);
if (ret)
@@ -637,14 +646,19 @@ unpin_out:
*
* The context life cycle is simple. The context refcount is incremented and
* decremented by 1 and create and destroy. If the context is in use by the GPU,
- * it will have a refoucnt > 1. This allows us to destroy the context abstract
+ * it will have a refcount > 1. This allows us to destroy the context abstract
* object while letting the normal object tracking destroy the backing BO.
+ *
+ * This function should not be used in execlists mode. Instead the context is
+ * switched by writing to the ELSP and requests keep a reference to their
+ * context.
*/
int i915_switch_context(struct intel_engine_cs *ring,
struct intel_context *to)
{
struct drm_i915_private *dev_priv = ring->dev->dev_private;

+ WARN_ON(i915.enable_execlists);
WARN_ON(!mutex_is_locked(&dev_priv->dev->struct_mutex));

if (to->legacy_hw_ctx.rcs_state == NULL) { /* We have the fake context */
--
1.7.9.5