[PATCH v3 25/28] drm/i915: Interrupt driven request completion

John.C.Harrison
2014-11-24T18:50:34Z

Added a hook to the ring noftification code to process request completion. This
means that there is no longer a need to explicitly process request completions
every time a request object is tested. Instead, the test code simply becomes
'return req->completed'. Obviously, this only works if ring interrupts are
enabled, however, this is already the case for the duration of __wait_request()
which is the point where the driver really needs to know.

To prevent stale requests floating around indefinitely, the retire work handler
also now performs a completion check periodically.

For: VIZ-4377
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Thomas Daniel <Thomas.Daniel@intel.com>
---
drivers/gpu/drm/i915/i915_drv.h | 5 -----
drivers/gpu/drm/i915/i915_gem.c | 10 ++++++++++
drivers/gpu/drm/i915/i915_irq.c | 2 ++
3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index d30823e..c969499 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2078,11 +2078,6 @@ static inline void i915_gem_request_assign(struct drm_i915_gem_request **pdst,
static inline bool i915_gem_request_completed(struct drm_i915_gem_request *req,
bool lazy_coherency)
{
- if (req->complete)
- return true;
-
- i915_gem_complete_requests_ring(req->ring, lazy_coherency);
-
return req->complete;
}

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 71fcbea..4aec1eb 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1239,6 +1239,11 @@ int __i915_wait_request(struct drm_i915_gem_request *req,
if (!irq_test_in_progress && WARN_ON(!ring->irq_get(ring)))
return -ENODEV;

+ /* Completion status should be interrupt driven but it is possible
+ * the request popped out before the interrupt was enabled. So do an
+ * explicit check now... */
+ i915_gem_complete_requests_ring(req->ring, false);
+
/* Record current time in case interrupted by signal, or wedged */
trace_i915_gem_request_wait_begin(req);
before = ktime_get_raw_ns();
@@ -2485,6 +2490,10 @@ int __i915_add_request(struct intel_engine_cs *ring,
list_add_tail(&request->list, &ring->request_list);
request->file_priv = NULL;

+ /* Avoid race condition where the request completes before it has
+ * been added to the list. */
+ ring->last_read_seqno = 0;
+
if (file) {
struct drm_i915_file_private *file_priv = file->driver_priv;

@@ -2868,6 +2877,7 @@ i915_gem_retire_requests(struct drm_device *dev)
int i;

for_each_ring(ring, dev_priv, i) {
+ i915_gem_complete_requests_ring(ring, false);
i915_gem_retire_requests_ring(ring);
idle &= list_empty(&ring->request_list);
if (i915.enable_execlists) {
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index b86b474..d425bb5 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1002,6 +1002,8 @@ static void notify_ring(struct drm_device *dev,

trace_i915_gem_request_complete(ring);

+ i915_gem_complete_requests_ring(ring, false);
+
wake_up_all(&ring->irq_queue);
}