[Intel-gfx] [PATCH 1/2] drm/i915/guc: Fix sleep under spinlock during reset

[Tvrtko Ursulin]

From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Looks like intel_guc_reset had the ability to sleep under the
uncore spinlock since forever but it wasn't detected until the
recent changes annotated the wait for register with might_sleep.

I have fixed it by removing holding of the uncore spinlock over
the call to gen6_hw_domain_reset, since I do not see that is
really needed. But there is always a possibility I am missing
some nasty detail so please double check.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
Cc: Arkadiusz Hiler <arkadiusz.hiler at intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
Cc: Oscar Mateo <oscar.mateo at intel.com>
--
A random selection of Cc for people who I though were recently
engaged in GuC code.
---
 drivers/gpu/drm/i915/intel_uncore.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index 0cd56bf00650..a10d8863b0a9 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -1532,7 +1532,7 @@ static int gen6_hw_domain_reset(struct drm_i915_private *dev_priv,
 	 */
 	__raw_i915_write32(dev_priv, GEN6_GDRST, hw_domain_mask);
 
-	/* Spin waiting for the device to ack the reset requests */
+	/* Wait for the device to ack the reset requests */
 	return intel_wait_for_register_fw(dev_priv,
 					  GEN6_GDRST, hw_domain_mask, 0,
 					  500);
@@ -1779,17 +1779,12 @@ bool intel_has_gpu_reset(struct drm_i915_private *dev_priv)
 int intel_guc_reset(struct drm_i915_private *dev_priv)
 {
 	int ret;
-	unsigned long irqflags;
 
 	if (!HAS_GUC(dev_priv))
 		return -EINVAL;
 
 	intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);
-	spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
-
 	ret = gen6_hw_domain_reset(dev_priv, GEN9_GRDOM_GUC);
-
-	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
 	intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
 
 	return ret;
-- 
2.9.3