drm/i915: Implement 16GB dimm wa for latency level-0
Memory with 16GB dimms require an increase of 1us in level-0 latency.
This patch implements the same.
Bspec: 4381
changes since V1:
- s/memdev_info/dram_info
- make skl_is_16gb_dimm pure function
Changes since V2:
- make is_16gb_dimm more generic
- rebase
Changes since V3:
- Simplify condition (Maarten)
Signed-off-by: Mahesh Kumar <mahesh1.kumar@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180831110942.9234-1-mahesh1.kumar@intel.com
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index d99e5fa..09463e3 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2875,6 +2875,16 @@ static void intel_read_wm_latency(struct drm_i915_private *dev_priv,
}
}
+ /*
+ * WA Level-0 adjustment for 16GB DIMMs: SKL+
+ * If we could not get dimm info enable this WA to prevent from
+ * 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)
+ wm[0] += 1;
+
} else if (IS_HASWELL(dev_priv) || IS_BROADWELL(dev_priv)) {
uint64_t sskpd = I915_READ64(MCH_SSKPD);