drm/radeon: rework fence handling, drop fence list v7

Using 64bits fence sequence we can directly compare sequence
number to know if a fence is signaled or not. Thus the fence
list became useless, so does the fence lock that mainly
protected the fence list.

Things like ring.ready are no longer behind a lock, this should
be ok as ring.ready is initialized once and will only change
when facing lockup. Worst case is that we return an -EBUSY just
after a successfull GPU reset, or we go into wait state instead
of returning -EBUSY (thus delaying reporting -EBUSY to fence
wait caller).

v2: Remove left over comment, force using writeback on cayman and
    newer, thus not having to suffer from possibly scratch reg
    exhaustion
v3: Rebase on top of change to uint64 fence patch
v4: Change DCE5 test to force write back on cayman and newer but
    also any APU such as PALM or SUMO family
v5: Rebase on top of new uint64 fence patch
v6: Just break if seq doesn't change any more. Use radeon_fence
    prefix for all function names. Even if it's now highly optimized,
    try avoiding polling to often.
v7: We should never poll the last_seq from the hardware without
    waking the sleeping threads, otherwise we might lose events.

Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Christian König <deathsimple@vodafone.de>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 1 insertions, 5 deletions

diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
index cdf46bc6dcc4..7c8711793421 100644
--- a/drivers/gpu/drm/radeon/radeon.h
+++ b/drivers/gpu/drm/radeon/radeon.h
@@ -263,15 +263,12 @@ struct radeon_fence_driver {
         atomic64_t                      last_seq;
         unsigned long                   last_activity;
         wait_queue_head_t               queue;
-        struct list_head                emitted;
-        struct list_head                signaled;
         bool                            initialized;
 };
 
 struct radeon_fence {
         struct radeon_device            *rdev;
         struct kref                     kref;
-        struct list_head                list;
         /* protected by radeon_fence.lock */
         uint64_t                        seq;
         /* RB, DMA, etc. */
@@ -291,7 +288,7 @@ int radeon_fence_wait_next(struct radeon_device *rdev, int ring);
 int radeon_fence_wait_empty(struct radeon_device *rdev, int ring);
 struct radeon_fence *radeon_fence_ref(struct radeon_fence *fence);
 void radeon_fence_unref(struct radeon_fence **fence);
-int radeon_fence_count_emitted(struct radeon_device *rdev, int ring);
+unsigned radeon_fence_count_emitted(struct radeon_device *rdev, int ring);
 
 /*
  * Tiling registers
@@ -1534,7 +1531,6 @@ struct radeon_device {
         struct radeon_mode_info         mode_info;
         struct radeon_scratch           scratch;
         struct radeon_mman              mman;
-        rwlock_t                        fence_lock;
         struct radeon_fence_driver      fence_drv[RADEON_NUM_RINGS];
         struct radeon_semaphore_driver  semaphore_drv;
         struct mutex                    ring_lock;