drm/i915/vlv: reset VLV media force wake request register

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@intel.com>
Reported-by: Darren Hart <dvhart@linux.intel.com>
Tested-by: Darren Hart <dvhart@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index f729dc71d5beb031599aca72f82c90ec946e2fe0..d0c75779d3f6f91e9cc98b0f1a853344783fdb48 100644 (file)
--- 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);
 }