drm/i915/display: fix level 0 adjustement on display ver >= 12
We should no longer increment level 0 by 1usec when we have 16Gb DIMMs.
Instead spec says to add 3usec (as opposed to 2) to each valid level
when punit replies 0 to level 0.
So set wm_lv_0_adjust_needed to false for DISPLAY_VER() >= 12 and set
the proper adjustment value when handling WaWmMemoryReadLatency.
Bspec: 49326, 4381
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210622212210.3746133-1-lucas.demarchi@intel.com
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 53f0e68..bd04e19 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2913,18 +2913,20 @@ static void intel_read_wm_latency(struct drm_i915_private *dev_priv,
}
/*
- * WaWmMemoryReadLatency:skl+,glk
+ * WaWmMemoryReadLatency
*
* punit doesn't take into account the read latency so we need
- * to add 2us to the various latency levels we retrieve from the
- * punit when level 0 response data us 0us.
+ * to add proper adjustement to each valid level we retrieve
+ * from the punit when level 0 response data is 0us.
*/
if (wm[0] == 0) {
- wm[0] += 2;
+ u8 adjust = DISPLAY_VER(dev_priv) >= 12 ? 3 : 2;
+
+ wm[0] += adjust;
for (level = 1; level <= max_level; level++) {
if (wm[level] == 0)
break;
- wm[level] += 2;
+ wm[level] += adjust;
}
}
@@ -2936,7 +2938,6 @@ static void intel_read_wm_latency(struct drm_i915_private *dev_priv,
*/
if (dev_priv->dram_info.wm_lv_0_adjust_needed)
wm[0] += 1;
-
} else if (IS_HASWELL(dev_priv) || IS_BROADWELL(dev_priv)) {
u64 sskpd = intel_uncore_read64(uncore, MCH_SSKPD);