drm/i915: Flush the CSB pointer reset

The HW resets it CSB tail pointer on resetting the engine. Most of the time. In case it doesn't (and for system resume) we write the expected value anyway. For extra paranoia, flush the write before we invalidate the cacheline. Signed-off-by: Chris Wilson <[email protected]> Cc: Mika Kuoppala <[email protected]> Acked-by: Mika Kuoppala <[email protected]> Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
modi0012 · Apr 12, 2019 · 0edda1d · 0edda1d
1 parent fa9d38f
commit 0edda1d
Showing 1 changed file with 1 addition and 0 deletions.
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1866,6 +1866,7 @@ static void reset_csb_pointers(struct intel_engine_execlists *execlists)
 	 */
 	execlists->csb_head = reset_value;
 	WRITE_ONCE(*execlists->csb_write, reset_value);
+	wmb(); /* Make sure this is visible to HW (paranoia?) */
 
 	invalidate_csb_entries(&execlists->csb_status[0],
 			       &execlists->csb_status[reset_value]);