[PATCH v3 19/29] drm/i915/wm: Do not make latency values monotonic on Xe3 onward

[Gustavo Sousa <gustavo.sousa@intel.com>]

The Windows driver is rejecting non-monotonic ranges latency values for
Xe3.  Let's make sure that we do not call make_wm_latency_monotonic()
for Xe3 and beyond.

Also, because of that, let's add a check at the end of
adjust_wm_latency() to ensure we raise a warning if the final list of
latency values is not monotonic.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>
---
 drivers/gpu/drm/i915/display/skl_watermark.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/skl_watermark.c b/drivers/gpu/drm/i915/display/skl_watermark.c
index d20c88ebe919..e13324af7afb 100644
--- a/drivers/gpu/drm/i915/display/skl_watermark.c
+++ b/drivers/gpu/drm/i915/display/skl_watermark.c
@@ -3211,6 +3211,18 @@ static void make_wm_latency_monotonic(struct intel_display *display)
 	}
 }
 
+static bool is_wm_latency_monotonic(struct intel_display *display)
+{
+	u16 *wm = display->wm.skl_latency;
+	int level, num_levels = display->wm.num_levels;
+
+	for (level = 1; level < num_levels; level++)
+		if (wm[level] < wm[level - 1])
+			return false;
+
+	return true;
+}
+
 static void
 adjust_wm_latency(struct intel_display *display)
 {
@@ -3221,7 +3233,8 @@ adjust_wm_latency(struct intel_display *display)
 
 	sanitize_wm_latency(display);
 
-	make_wm_latency_monotonic(display);
+	if (DISPLAY_VER(display) < 30)
+		make_wm_latency_monotonic(display);
 
 	/*
 	 * WaWmMemoryReadLatency
@@ -3241,6 +3254,8 @@ adjust_wm_latency(struct intel_display *display)
 	 */
 	if (need_16gb_dimm_wa(display))
 		increase_wm_latency(display, 1);
+
+	drm_WARN_ON(display->drm, !is_wm_latency_monotonic(display));
 }
 
 static void mtl_read_wm_latency(struct intel_display *display)

-- 
2.51.0