drm/i915: fix the transition minimums for gen9+ watermarks

The transition minimum is 14 blocks for gens 9 and 10, and 4 blocks
for gen 11. This minimum value is supposed to be added to the
configurable trans_amount. This matches both BSpec and additional
information provided by our HW engineers.

Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181004231600.14101-3-paulo.r.zanoni@intel.com

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 1392aa56a55aed28c8629d0d13b8be94e88a133a..983af46197b115d7b0336dc5cf539b8f12acded9 100644 (file)
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -4875,8 +4875,8 @@ static void skl_compute_transition_wm(struct intel_crtc_state *cstate,
        if (!dev_priv->ipc_enabled)
                goto exit;
 
-       trans_min = 0;
-       if (INTEL_GEN(dev_priv) >= 10)
+       trans_min = 14;
+       if (INTEL_GEN(dev_priv) >= 11)
                trans_min = 4;
 
        trans_offset_b = trans_min + trans_amount;