[Intel-gfx] [PATCH] drm/i915: Skip wm/ddb readout for disabled pipes

[Ville Syrjala <ville.syrjala@linux.intel.com>]

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

The stuff programmed into the wm/ddb registers of planes
on disabled pipes doesn't matter. So during readout just
leave our software state tracking for those zeroed.

This should avoid us trying too hard to clean up after
whatever mess the VBIOS/GOP left in there. The actual
hardware state will get cleaned up if/when we enable
the pipe anyway.

References: https://gitlab.freedesktop.org/drm/intel/-/issues/5711
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/intel_pm.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 174fab564d10..d083964d5470 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -6560,7 +6560,10 @@ void skl_wm_get_hw_state(struct drm_i915_private *dev_priv)
 		enum plane_id plane_id;
 		u8 slices;
 
-		skl_pipe_wm_get_hw_state(crtc, &crtc_state->wm.skl.optimal);
+		memset(&crtc_state->wm.skl.optimal, 0,
+		       sizeof(crtc_state->wm.skl.optimal));
+		if (crtc_state->hw.active)
+			skl_pipe_wm_get_hw_state(crtc, &crtc_state->wm.skl.optimal);
 		crtc_state->wm.skl.raw = crtc_state->wm.skl.optimal;
 
 		memset(&dbuf_state->ddb[pipe], 0, sizeof(dbuf_state->ddb[pipe]));
@@ -6571,6 +6574,9 @@ void skl_wm_get_hw_state(struct drm_i915_private *dev_priv)
 			struct skl_ddb_entry *ddb_y =
 				&crtc_state->wm.skl.plane_ddb_y[plane_id];
 
+			if (!crtc_state->hw.active)
+				continue;
+
 			skl_ddb_get_hw_plane_state(dev_priv, crtc->pipe,
 						   plane_id, ddb, ddb_y);
 
-- 
2.35.1