drm/i915/psr: Only allow PSR in LPSP mode on HSW non-ULT

From Ville Syrjala
02cfae7d62783614b433ec93b2ccf9d9fba212ff in linux-6.6.y/6.6.15
f9f031dd21a7ce13a13862fa5281d32e1029c70f in mainline linux

diff --git a/sys/dev/pci/drm/i915/display/intel_psr.c b/sys/dev/pci/drm/i915/display/intel_psr.c
index f479589..702c6a8 100644 (file)
--- a/sys/dev/pci/drm/i915/display/intel_psr.c
+++ b/sys/dev/pci/drm/i915/display/intel_psr.c
@@ -1400,8 +1400,18 @@ static void intel_psr_enable_source(struct intel_dp *intel_dp,
         * can rely on frontbuffer tracking.
         */
        mask = EDP_PSR_DEBUG_MASK_MEMUP |
-              EDP_PSR_DEBUG_MASK_HPD |
-              EDP_PSR_DEBUG_MASK_LPSP;
+              EDP_PSR_DEBUG_MASK_HPD;
+
+       /*
+        * For some unknown reason on HSW non-ULT (or at least on
+        * Dell Latitude E6540) external displays start to flicker
+        * when PSR is enabled on the eDP. SR/PC6 residency is much
+        * higher than should be possible with an external display.
+        * As a workaround leave LPSP unmasked to prevent PSR entry
+        * when external displays are active.
+        */
+       if (DISPLAY_VER(dev_priv) >= 8 || IS_HASWELL_ULT(dev_priv))
+               mask |= EDP_PSR_DEBUG_MASK_LPSP;
 
        if (DISPLAY_VER(dev_priv) < 20)
                mask |= EDP_PSR_DEBUG_MASK_MAX_SLEEP;