[Intel-gfx] [PATCH] CHROMIUM: drm/i915: tune the RC6 timeout for stability

[james.ausmus at intel.com]

From: Stéphane Marchesin <marcheu at chromium.org>

It's basically the same deal as the RC6+ issues on ivy bridge
(https://gerrit.chromium.org/gerrit/#/c/42655/) except this
time with RC6 on sandy bridge. Like last time the core of the
issue is that the existing timings don't work 100% with our
voltage regulator, so once in a couple suspend/resumes the
kernel will print a warning message about the GPU not getting
out of RC6.

Luckily this time the shared timings are already working (from
the ivy bridge work) so we only need to adjust the one
RC6-specific timing, GEN6_RC6_THRESHOLD.

Just like with the RC6+ change, I couldn't see any measurable
power difference with an idle lumpy.

BUG=chromium:235116
TEST=ran the power_Resume a bunch on stumpy, didn't see an RC6 error
TEST=tested lumpy for power regressions on idle

Change-Id: I0e1be040e0e156cd38d6c396e237d4a01a16a6a2
Reviewed-on: https://gerrit.chromium.org/gerrit/57868
Reviewed-by: Vincent Palatin <vpalatin at chromium.org>
Commit-Queue: Stéphane Marchesin <marcheu at chromium.org>
Tested-by: Stéphane Marchesin <marcheu at chromium.org>
---
 drivers/gpu/drm/i915/intel_pm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 1b487cb..8105d10 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2572,7 +2572,7 @@ static void gen6_enable_rps(struct drm_device *dev)
 
 	I915_WRITE(GEN6_RC_SLEEP, 0);
 	I915_WRITE(GEN6_RC1e_THRESHOLD, 1000);
-	I915_WRITE(GEN6_RC6_THRESHOLD, 50000);
+	I915_WRITE(GEN6_RC6_THRESHOLD, 150000);
 	I915_WRITE(GEN6_RC6p_THRESHOLD, 150000);
 	I915_WRITE(GEN6_RC6pp_THRESHOLD, 64000); /* unused */
 
-- 
1.8.3.2