[Intel-gfx] [PATCH v2 2/3] drm/i915/gen9: Compute data rates for all planes on first commit

[Matt Roper]

When we sanitize our DDB and watermark info during the first atomic
commit, we need to calculate the total data rate.  Since we haven't
explicitly added the planes for each CRTC to our atomic state, the total
data rate calculation will try to use the cached values from a previous
commit (which are 0 since there was no previous commit); this result is
incorrect if we inherited any active planes from the BIOS.

During our very first atomic commit, we need to explicitly add all
active planes to the atomic state to ensure that valid data rate values
are calculated for them.  Subsequent commits will then have valid cached
values to fall back on.

Reported-by: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_pm.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index c06a8a3..4c425f6 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3939,6 +3939,18 @@ skl_compute_ddb(struct drm_atomic_state *state)
 		if (IS_ERR(cstate))
 			return PTR_ERR(cstate);
 
+		/*
+		 * If this is our first commit after hw readout, we don't have
+		 * valid data rate values cached.  Add all planes to ensure we
+		 * calculate a valid data rate.
+		 */
+		if (dev_priv->wm.distrust_bios_wm) {
+			ret = drm_atomic_add_affected_planes(state,
+							     &intel_crtc->base);
+			if (ret)
+				return ret;
+		}
+
 		ret = skl_allocate_pipe_ddb(cstate, ddb);
 		if (ret)
 			return ret;
-- 
2.1.4