From 0b83c01f873f749723e22c167ced05b9c9750b1d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@linux.intel.com>
Date: Thu, 3 Mar 2022 21:12:05 +0200
Subject: drm/i915: Properly write lock bw_state when it changes
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Git-commit: 6731eb046cf71e30a79e60bae8ed31f5450928fa
Patch-mainline: v5.19-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

The current code also forgets to call intel_atomic_lock_global_state()
when other stuff besides the final min_cdlck changes in the state.
That means we may throw away data which actually has changed, and
thus we can't be at all sure what the code ends up doing during
subsequent commits. Do the write lock properly.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220303191207.27931-8-ville.syrjala@linux.intel.com
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/i915/display/intel_bw.c | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_bw.c b/drivers/gpu/drm/i915/display/intel_bw.c
index 8155f2309f80..a0a69d8db132 100644
--- a/drivers/gpu/drm/i915/display/intel_bw.c
+++ b/drivers/gpu/drm/i915/display/intel_bw.c
@@ -678,6 +678,28 @@ intel_atomic_get_bw_state(struct intel_atomic_state *state)
 	return to_intel_bw_state(bw_state);
 }
 
+static bool intel_bw_state_changed(struct drm_i915_private *i915,
+				   const struct intel_bw_state *old_bw_state,
+				   const struct intel_bw_state *new_bw_state)
+{
+	enum pipe pipe;
+
+	for_each_pipe(i915, pipe) {
+		const struct intel_dbuf_bw *old_crtc_bw =
+			&old_bw_state->dbuf_bw[pipe];
+		const struct intel_dbuf_bw *new_crtc_bw =
+			&new_bw_state->dbuf_bw[pipe];
+		enum dbuf_slice slice;
+
+		for_each_dbuf_slice(i915, slice) {
+			if (old_crtc_bw->used_bw[slice] != new_crtc_bw->used_bw[slice])
+				return true;
+		}
+	}
+
+	return old_bw_state->min_cdclk != new_bw_state->min_cdclk;
+}
+
 static void skl_crtc_calc_dbuf_bw(struct intel_bw_state *bw_state,
 				  const struct intel_crtc_state *crtc_state)
 {
@@ -765,7 +787,7 @@ int intel_bw_calc_min_cdclk(struct intel_atomic_state *state)
 
 	new_bw_state->min_cdclk = DIV_ROUND_UP(max_bw, 64);
 
-	if (new_bw_state->min_cdclk != old_bw_state->min_cdclk) {
+	if (intel_bw_state_changed(dev_priv, old_bw_state, new_bw_state)) {
 		int ret = intel_atomic_lock_global_state(&new_bw_state->base);
 
 		if (ret)
-- 
2.38.1