[Intel-gfx] [PATCH 1/2] drm/i915/gen6+: Clear upper data byte during PCODE write

[Imre Deak]

The spec calls for the upper data byte to be cleared before most of the
PCODE write commands, for others like IPS control it doesn't say
anything about this byte. Let's clear it in case it's clobbered somehow,
especially that there are places where we only do a PCODE write without
a preceeding PCODE read.

Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Signed-off-by: Imre Deak <imre.deak at intel.com>
---
 drivers/gpu/drm/i915/intel_pm.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 29b6653..66c62f3 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -7838,6 +7838,7 @@ int sandybridge_pcode_write(struct drm_i915_private *dev_priv,
 	}
 
 	I915_WRITE_FW(GEN6_PCODE_DATA, val);
+	I915_WRITE_FW(GEN6_PCODE_DATA1, 0);
 	I915_WRITE_FW(GEN6_PCODE_MAILBOX, GEN6_PCODE_READY | mbox);
 
 	if (intel_wait_for_register_fw(dev_priv,
-- 
2.5.0