drm/i915: Unify intel_ring_begin()
Combine the near identical implementations of intel_logical_ring_begin()
and intel_ring_begin() - the only difference is that the logical wait
has to check for a matching ring (which is assumed by legacy).
In the process some debug messages are culled as there were following a
WARN if we hit an actual error.
v2: Updated commentary
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1461833819-3991-12-git-send-email-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 461ea71..87822b6 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -53,12 +53,6 @@
ringbuf->tail, ringbuf->size);
}
-int intel_ring_space(struct intel_ringbuffer *ringbuf)
-{
- intel_ring_update_space(ringbuf);
- return ringbuf->space;
-}
-
bool intel_engine_stopped(struct intel_engine_cs *engine)
{
struct drm_i915_private *dev_priv = engine->dev->dev_private;
@@ -2325,51 +2319,6 @@
engine->dev = NULL;
}
-static int ring_wait_for_space(struct intel_engine_cs *engine, int n)
-{
- struct intel_ringbuffer *ringbuf = engine->buffer;
- struct drm_i915_gem_request *request;
- unsigned space;
- int ret;
-
- if (intel_ring_space(ringbuf) >= n)
- return 0;
-
- /* The whole point of reserving space is to not wait! */
- WARN_ON(ringbuf->reserved_in_use);
-
- list_for_each_entry(request, &engine->request_list, list) {
- space = __intel_ring_space(request->postfix, ringbuf->tail,
- ringbuf->size);
- if (space >= n)
- break;
- }
-
- if (WARN_ON(&request->list == &engine->request_list))
- return -ENOSPC;
-
- ret = i915_wait_request(request);
- if (ret)
- return ret;
-
- ringbuf->space = space;
- return 0;
-}
-
-static void __wrap_ring_buffer(struct intel_ringbuffer *ringbuf)
-{
- uint32_t __iomem *virt;
- int rem = ringbuf->size - ringbuf->tail;
-
- virt = ringbuf->virtual_start + ringbuf->tail;
- rem /= 4;
- while (rem--)
- iowrite32(MI_NOOP, virt++);
-
- ringbuf->tail = 0;
- intel_ring_update_space(ringbuf);
-}
-
int intel_engine_idle(struct intel_engine_cs *engine)
{
struct drm_i915_gem_request *req;
@@ -2411,63 +2360,82 @@
void intel_ring_reserved_space_reserve(struct intel_ringbuffer *ringbuf, int size)
{
- WARN_ON(ringbuf->reserved_size);
- WARN_ON(ringbuf->reserved_in_use);
-
+ GEM_BUG_ON(ringbuf->reserved_size);
ringbuf->reserved_size = size;
}
void intel_ring_reserved_space_cancel(struct intel_ringbuffer *ringbuf)
{
- WARN_ON(ringbuf->reserved_in_use);
-
+ GEM_BUG_ON(!ringbuf->reserved_size);
ringbuf->reserved_size = 0;
- ringbuf->reserved_in_use = false;
}
void intel_ring_reserved_space_use(struct intel_ringbuffer *ringbuf)
{
- WARN_ON(ringbuf->reserved_in_use);
-
- ringbuf->reserved_in_use = true;
- ringbuf->reserved_tail = ringbuf->tail;
+ GEM_BUG_ON(!ringbuf->reserved_size);
+ ringbuf->reserved_size = 0;
}
void intel_ring_reserved_space_end(struct intel_ringbuffer *ringbuf)
{
- WARN_ON(!ringbuf->reserved_in_use);
- if (ringbuf->tail > ringbuf->reserved_tail) {
- WARN(ringbuf->tail > ringbuf->reserved_tail + ringbuf->reserved_size,
- "request reserved size too small: %d vs %d!\n",
- ringbuf->tail - ringbuf->reserved_tail, ringbuf->reserved_size);
- } else {
- /*
- * The ring was wrapped while the reserved space was in use.
- * That means that some unknown amount of the ring tail was
- * no-op filled and skipped. Thus simply adding the ring size
- * to the tail and doing the above space check will not work.
- * Rather than attempt to track how much tail was skipped,
- * it is much simpler to say that also skipping the sanity
- * check every once in a while is not a big issue.
- */
- }
-
- ringbuf->reserved_size = 0;
- ringbuf->reserved_in_use = false;
+ GEM_BUG_ON(ringbuf->reserved_size);
}
-static int __intel_ring_prepare(struct intel_engine_cs *engine, int bytes)
+static int wait_for_space(struct drm_i915_gem_request *req, int bytes)
{
- struct intel_ringbuffer *ringbuf = engine->buffer;
- int remain_usable = ringbuf->effective_size - ringbuf->tail;
+ struct intel_ringbuffer *ringbuf = req->ringbuf;
+ struct intel_engine_cs *engine = req->engine;
+ struct drm_i915_gem_request *target;
+
+ intel_ring_update_space(ringbuf);
+ if (ringbuf->space >= bytes)
+ return 0;
+
+ /*
+ * Space is reserved in the ringbuffer for finalising the request,
+ * as that cannot be allowed to fail. During request finalisation,
+ * reserved_space is set to 0 to stop the overallocation and the
+ * assumption is that then we never need to wait (which has the
+ * risk of failing with EINTR).
+ *
+ * See also i915_gem_request_alloc() and i915_add_request().
+ */
+ GEM_BUG_ON(!ringbuf->reserved_size);
+
+ list_for_each_entry(target, &engine->request_list, list) {
+ unsigned space;
+
+ /*
+ * The request queue is per-engine, so can contain requests
+ * from multiple ringbuffers. Here, we must ignore any that
+ * aren't from the ringbuffer we're considering.
+ */
+ if (target->ringbuf != ringbuf)
+ continue;
+
+ /* Would completion of this request free enough space? */
+ space = __intel_ring_space(target->postfix, ringbuf->tail,
+ ringbuf->size);
+ if (space >= bytes)
+ break;
+ }
+
+ if (WARN_ON(&target->list == &engine->request_list))
+ return -ENOSPC;
+
+ return i915_wait_request(target);
+}
+
+int intel_ring_begin(struct drm_i915_gem_request *req, int num_dwords)
+{
+ struct intel_ringbuffer *ringbuf = req->ringbuf;
int remain_actual = ringbuf->size - ringbuf->tail;
- int ret, total_bytes, wait_bytes = 0;
+ int remain_usable = ringbuf->effective_size - ringbuf->tail;
+ int bytes = num_dwords * sizeof(u32);
+ int total_bytes, wait_bytes;
bool need_wrap = false;
- if (ringbuf->reserved_in_use)
- total_bytes = bytes;
- else
- total_bytes = bytes + ringbuf->reserved_size;
+ total_bytes = bytes + ringbuf->reserved_size;
if (unlikely(bytes > remain_usable)) {
/*
@@ -2476,44 +2444,40 @@
*/
wait_bytes = remain_actual + total_bytes;
need_wrap = true;
+ } else if (unlikely(total_bytes > remain_usable)) {
+ /*
+ * The base request will fit but the reserved space
+ * falls off the end. So we don't need an immediate wrap
+ * and only need to effectively wait for the reserved
+ * size space from the start of ringbuffer.
+ */
+ wait_bytes = remain_actual + ringbuf->reserved_size;
} else {
- if (unlikely(total_bytes > remain_usable)) {
- /*
- * The base request will fit but the reserved space
- * falls off the end. So don't need an immediate wrap
- * and only need to effectively wait for the reserved
- * size space from the start of ringbuffer.
- */
- wait_bytes = remain_actual + ringbuf->reserved_size;
- } else if (total_bytes > ringbuf->space) {
- /* No wrapping required, just waiting. */
- wait_bytes = total_bytes;
- }
+ /* No wrapping required, just waiting. */
+ wait_bytes = total_bytes;
}
- if (wait_bytes) {
- ret = ring_wait_for_space(engine, wait_bytes);
+ if (wait_bytes > ringbuf->space) {
+ int ret = wait_for_space(req, wait_bytes);
if (unlikely(ret))
return ret;
- if (need_wrap)
- __wrap_ring_buffer(ringbuf);
+ intel_ring_update_space(ringbuf);
}
- return 0;
-}
+ if (unlikely(need_wrap)) {
+ GEM_BUG_ON(remain_actual > ringbuf->space);
+ GEM_BUG_ON(ringbuf->tail + remain_actual > ringbuf->size);
-int intel_ring_begin(struct drm_i915_gem_request *req,
- int num_dwords)
-{
- struct intel_engine_cs *engine = req->engine;
- int ret;
+ /* Fill the tail with MI_NOOP */
+ memset(ringbuf->virtual_start + ringbuf->tail,
+ 0, remain_actual);
+ ringbuf->tail = 0;
+ ringbuf->space -= remain_actual;
+ }
- ret = __intel_ring_prepare(engine, num_dwords * sizeof(uint32_t));
- if (ret)
- return ret;
-
- engine->buffer->space -= num_dwords * sizeof(uint32_t);
+ ringbuf->space -= bytes;
+ GEM_BUG_ON(ringbuf->space < 0);
return 0;
}