[5/9] drm/i915: Skip reset request if there is one already

Submitted by Michel Thierry on Dec. 16, 2016, 8:20 p.m.

Details

Message ID 20161216202010.7983-6-michel.thierry@intel.com
State New
Headers show
Series "Execlist based engine-reset" ( rev: 1 ) in Intel GFX

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Commit Message

Michel Thierry Dec. 16, 2016, 8:20 p.m.
From: Mika Kuoppala <mika.kuoppala@linux.intel.com>

To perform engine reset we first disable engine to capture its state. This
is done by issuing a reset request. Because we are reusing existing
infrastructure, again when we actually reset an engine, reset function
checks engine mask and issues reset request again which is unnecessary. To
avoid this we check if the engine is already prepared, if so we just exit
from that point.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Signed-off-by: Arun Siluvery <arun.siluvery@linux.intel.com>
Signed-off-by: Michel Thierry <michel.thierry@intel.com>
---
 drivers/gpu/drm/i915/intel_uncore.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

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diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index 9105c166a6d5..cd3102d841a4 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -1761,10 +1761,15 @@  int intel_wait_for_register(struct drm_i915_private *dev_priv,
 static int gen8_engine_reset_begin(struct intel_engine_cs *engine)
 {
 	struct drm_i915_private *dev_priv = engine->i915;
+	const i915_reg_t reset_ctrl = RING_RESET_CTL(engine->mmio_base);
+	const u32 ready = RESET_CTL_REQUEST_RESET | RESET_CTL_READY_TO_RESET;
 	int ret;
 
-	I915_WRITE_FW(RING_RESET_CTL(engine->mmio_base),
-		      _MASKED_BIT_ENABLE(RESET_CTL_REQUEST_RESET));
+	/* If engine has been already prepared, we can shortcut here */
+	if ((I915_READ_FW(reset_ctrl) & ready) == ready)
+		return 0;
+
+	I915_WRITE_FW(reset_ctrl, _MASKED_BIT_ENABLE(RESET_CTL_REQUEST_RESET));
 
 	ret = intel_wait_for_register_fw(dev_priv,
 					 RING_RESET_CTL(engine->mmio_base),