*/
void amdgpu_fence_process(struct amdgpu_ring *ring)
{
- uint64_t seq, last_seq, last_emitted;
- unsigned count_loop = 0;
- bool wake = false;
- unsigned long irqflags;
-
- /* Note there is a scenario here for an infinite loop but it's
- * very unlikely to happen. For it to happen, the current polling
- * process need to be interrupted by another process and another
- * process needs to update the last_seq btw the atomic read and
- * xchg of the current process.
- *
- * More over for this to go in infinite loop there need to be
- * continuously new fence signaled ie amdgpu_fence_read needs
- * to return a different value each time for both the currently
- * polling process and the other process that xchg the last_seq
- * btw atomic read and xchg of the current process. And the
- * value the other process set as last seq must be higher than
- * the seq value we just read. Which means that current process
- * need to be interrupted after amdgpu_fence_read and before
- * atomic xchg.
- *
- * To be even more safe we count the number of time we loop and
- * we bail after 10 loop just accepting the fact that we might
- * have temporarly set the last_seq not to the true real last
- * seq but to an older one.
- */
- spin_lock_irqsave(&ring->fence_lock, irqflags);
- last_seq = atomic64_read(&ring->fence_drv.last_seq);
- do {
- last_emitted = ring->fence_drv.sync_seq[ring->idx];
- seq = amdgpu_fence_read(ring);
- seq |= last_seq & 0xffffffff00000000LL;
- if (seq < last_seq) {
- seq &= 0xffffffff;
- seq |= last_emitted & 0xffffffff00000000LL;
- }
-
- if (seq <= last_seq || seq > last_emitted) {
- break;
- }
- /* If we loop over we don't want to return without
- * checking if a fence is signaled as it means that the
- * seq we just read is different from the previous on.
- */
- wake = true;
- last_seq = seq;
- if ((count_loop++) > 10) {
- /* We looped over too many time leave with the
- * fact that we might have set an older fence
- * seq then the current real last seq as signaled
- * by the hw.
- */
- break;
- }
- } while (atomic64_xchg(&ring->fence_drv.last_seq, seq) > seq);
-
- if (wake)
+ if (amdgpu_fence_activity(ring))
wake_up_all(&ring->fence_drv.fence_queue);
- spin_unlock_irqrestore(&ring->fence_lock, irqflags);
}
/**