drm/i915/ringbuffer: 2-step restart (b7f21899) · Commits · 戴 / test

We may be simply restarting too fast for the culmudgeonly gen3/gen4 as we still see missing interrupts following a reset. So let's try restarting a little slower, first wake up the ring empty and then tell it about the work it has to perform. References: https://bugs.freedesktop.org/show_bug.cgi?id=108735 Signed-off-by:

Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by:

Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20181126122821.4537-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/intel_ringbuffer.c

+9 −2

Original line number	Diff line number	Diff line
		@@ -546,10 +546,11 @@ static int init_ring_common(struct intel_engine_cs *engine)
		/* Check that the ring offsets point within the ring! */
		GEM_BUG_ON(!intel_ring_offset_valid(ring, ring->head));
		GEM_BUG_ON(!intel_ring_offset_valid(ring, ring->tail));

		intel_ring_update_space(ring);

		/* First wake the ring up to an empty/idle ring */
		I915_WRITE_HEAD(engine, ring->head);
		I915_WRITE_TAIL(engine, ring->tail);
		I915_WRITE_TAIL(engine, ring->head);
		(void)I915_READ_TAIL(engine);

		I915_WRITE_CTL(engine, RING_CTL_SIZE(ring->size) \| RING_VALID);
		@@ -574,6 +575,12 @@ static int init_ring_common(struct intel_engine_cs *engine)
		if (INTEL_GEN(dev_priv) > 2)
		I915_WRITE_MODE(engine, _MASKED_BIT_DISABLE(STOP_RING));

		/* Now awake, let it get started */
		if (ring->tail != ring->head) {
		I915_WRITE_TAIL(engine, ring->tail);
		(void)I915_READ_TAIL(engine);
		}

		/* Papering over lost _interrupts_ immediately following the restart */
		intel_engine_wakeup(engine);
		out:

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