Although the mmio are uncached and so should be flushed on every write, be paranoid and do a mmio read after setting the ring head/tail to be sure they have taken effect before moving on. v2: post tail to be pleasing to the eye Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx> --- drivers/gpu/drm/i915/intel_uncore.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c index 164dbb8cfa36..0fd59dd6bbb5 100644 --- a/drivers/gpu/drm/i915/intel_uncore.c +++ b/drivers/gpu/drm/i915/intel_uncore.c @@ -1522,9 +1522,11 @@ static void gen3_stop_engine(struct intel_engine_cs *engine) engine->name); I915_WRITE_FW(RING_HEAD(base), I915_READ_FW(RING_TAIL(base))); + POSTING_READ_FW(RING_HEAD(base)); /* paranoia */ I915_WRITE_FW(RING_HEAD(base), 0); I915_WRITE_FW(RING_TAIL(base), 0); + POSTING_READ_FW(RING_TAIL(base)); /* The ring must be empty before it is disabled */ I915_WRITE_FW(RING_CTL(base), 0); -- 2.16.1 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
