drm/i915: Don't apply the 16Gb DIMM wm latency w/a to BXT/GLK
The 16Gb DIMM w/a is not applicable to BXT or GLK. Limit it to
the appropriate platforms.
This was especially harsh on GLK since we don't even try to read
the DIMM information on that platforms, hence valid_dimm was
always false and thus we always tried to apply the w/a.
Furthermore the w/a pushed the level 0 latency above the
level 1 latency, which doesn't really make sense.
v2: Do the check when populating is_16gb_dimm (Mahesh)
Cc: Mahesh Kumar <mahesh1.kumar@intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Fixes: 86b592876cb6 ("drm/i915: Implement 16GB dimm wa for latency level-0")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181023182102.31549-1-ville.syrjala@linux.intel.com
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Mahesh Kumar <mahesh1.sh.kumar@gmail.com>
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 7b49b3c..688298c 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2881,8 +2881,7 @@ static void intel_read_wm_latency(struct drm_i915_private *dev_priv,
* any underrun. If not able to get Dimm info assume 16GB dimm
* to avoid any underrun.
*/
- if (!dev_priv->dram_info.valid_dimm ||
- dev_priv->dram_info.is_16gb_dimm)
+ if (dev_priv->dram_info.is_16gb_dimm)
wm[0] += 1;
} else if (IS_HASWELL(dev_priv) || IS_BROADWELL(dev_priv)) {