[Intel-gfx] [PATCH] drm/i915/skl: Correct other-pipe watermark update condition check (v2)

[Matt Roper]

From: "Kumar, Mahesh" <mahesh1.kumar at intel.com>

If ddb allocation for planes in current CRTC is changed, that doesn't
lead to ddb allocation change for other CRTCs, because our DDB allocation
is not dynamic according to plane parameters, ddb is allocated according
to number of CRTC enabled, & divided equally among CTRC's.

In current condition check during Watermark calculation, if number of
plane/ddb allocation changes for current CRTC, Watermark for other pipes
are recalculated. But there is no change in DDB allocation of other pipe
so watermark is also not changed, This leads to warning messages.
WARN_ON(!wm_changed)

This patch corrects this and check if DDB allocation for pipes is changed,
then only recalculate watermarks.

v2 (by Matt): Rebased to latest -nightly and fixed a typo

Signed-off-by: Kumar, Mahesh <mahesh1.kumar at intel.com>
Reviewed-by(v1): Ville Syrjälä <ville.syrjala at linux.intel.com>
Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
---
I don't think this solves all the !wm_changed warnings (I still see one during
fbdev restore following various igt tests), but it seems like a move in the
right direction so I figured I'd go ahead and rebase Mahesh' patch so it can
get merged.

 drivers/gpu/drm/i915/intel_pm.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 0fb0459..0467e34 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3064,14 +3064,12 @@ static bool skl_ddb_allocation_changed(const struct skl_ddb_allocation *new_ddb,
 	struct drm_device *dev = intel_crtc->base.dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	const struct skl_ddb_allocation *cur_ddb = &dev_priv->wm.skl_hw.ddb;
-	enum pipe pipe = intel_crtc->pipe;
-
-	if (memcmp(new_ddb->plane[pipe], cur_ddb->plane[pipe],
-		   sizeof(new_ddb->plane[pipe])))
-		return true;
 
-	if (memcmp(&new_ddb->plane[pipe][PLANE_CURSOR], &cur_ddb->plane[pipe][PLANE_CURSOR],
-		    sizeof(new_ddb->plane[pipe][PLANE_CURSOR])))
+	/*
+	 * If ddb allocation of pipes changed, it may require recalculation of
+	 * watermarks
+	 */
+	if (memcmp(new_ddb->pipe, cur_ddb->pipe, sizeof(new_ddb->pipe)))
 		return true;
 
 	return false;
-- 
2.1.4