From: Sameer Nanda <[email protected]> On Sandybridge/Ivybridge platforms, a higher RC6_THRESHOLD is required for stability reasons. On Haswell, however, this higher setting is resulting in an additional ~800mW of power consumption in light GPU usage scenarios such as blinking cursor. Lowering RC6_THRESHOLD to 50000 on Haswell does not seem to cause stability issues.
Therefore, on SNB/IVB keep the higher threshold for stability reasons, but on HSW use the default 50000 threshold for power saving reasons. BUG=chrome-os-partner:20744 TEST=1. On SNB (lumpy) and IVB (link) systems, "intel_reg_read 0xa0b8" command should return 0x1E848. 2. On Haswell systems, "intel_reg_read 0xa0b8" command should return 0xC350. Change-Id: I2f7d5895b925dcf3ff96a2756e699797bda4104d Signed-off-by: Sameer Nanda <[email protected]> Reviewed-on: https://gerrit.chromium.org/gerrit/61302 Reviewed-by: Stéphane Marchesin <[email protected]> --- drivers/gpu/drm/i915/intel_pm.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c index a701495..56e65f9 100644 --- a/drivers/gpu/drm/i915/intel_pm.c +++ b/drivers/gpu/drm/i915/intel_pm.c @@ -3166,7 +3166,10 @@ 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, 125000); + if (INTEL_INFO(dev)->gen <= 6 || IS_IVYBRIDGE(dev)) + I915_WRITE(GEN6_RC6_THRESHOLD, 125000); + else + I915_WRITE(GEN6_RC6_THRESHOLD, 50000); I915_WRITE(GEN6_RC6p_THRESHOLD, 150000); I915_WRITE(GEN6_RC6pp_THRESHOLD, 64000); /* unused */ -- 1.8.3.2 _______________________________________________ Intel-gfx mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/intel-gfx
