[Intel-gfx] [PATCH] drm/i915/vlv: reset VLV media force wake request register

[Jani Nikula]

Media force wake get hangs the machine when the system is booted without
displays attached. The assumption is that (at least some versions of)
the firmware has skipped some initialization in that case.

Empirical evidence suggests we need to reset the media force wake
request register in addition to the render one to avoid hangs.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=75895
Reported-by: Imre Deak <imre.deak at intel.com>
Reported-by: Darren Hart <dvhart at linux.intel.com>
Cc: stable at vger.kernel.org
Signed-off-by: Jani Nikula <jani.nikula at intel.com>

---

Darren, a Tested-by would be much appreciated!

Thanks,
Jani.
---
 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 76dc185793ce..27fe2df47d73 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -185,6 +185,8 @@ static void vlv_force_wake_reset(struct drm_i915_private *dev_priv)
 {
 	__raw_i915_write32(dev_priv, FORCEWAKE_VLV,
 			   _MASKED_BIT_DISABLE(0xffff));
+	__raw_i915_write32(dev_priv, FORCEWAKE_MEDIA_VLV,
+			   _MASKED_BIT_DISABLE(0xffff));
 	/* something from same cacheline, but !FORCEWAKE_VLV */
 	__raw_posting_read(dev_priv, FORCEWAKE_ACK_VLV);
 }
-- 
1.9.1