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* [PATCH] drm/i915/power_well: Enable workaround for DSS clock gating issue (22021048059)
@ 2026-01-28  7:48 Mika Kahola
  2026-01-28 10:14 ` ✗ i915.CI.BAT: failure for " Patchwork
                   ` (2 more replies)
  0 siblings, 3 replies; 6+ messages in thread
From: Mika Kahola @ 2026-01-28  7:48 UTC (permalink / raw)
  To: intel-gfx, intel-xe; +Cc: Mika Kahola

Prevent display corruption observed after restart, hotplug, or unplug
operations on Meteor Lake and newer platforms. The issue is caused by
DSS clock gating affecting DSC logic when pipe power wells are disabled.

Apply WA 22021048059 by disabling DSS clock gating for the affected pipes
before turning off their power wells. This avoids DSC corruption on
external displays.

WA: 22021048059
BSpec: 690991, 666241

Signed-off-by: Mika Kahola <mika.kahola@intel.com>
---
 .../i915/display/intel_display_power_well.c   | 78 ++++++++++++++++++-
 .../gpu/drm/i915/display/intel_display_regs.h |  7 ++
 .../gpu/drm/i915/display/intel_display_wa.c   |  2 +
 .../gpu/drm/i915/display/intel_display_wa.h   |  1 +
 4 files changed, 86 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display_power_well.c b/drivers/gpu/drm/i915/display/intel_display_power_well.c
index 6f9bc6f9615e..1ef450f26879 100644
--- a/drivers/gpu/drm/i915/display/intel_display_power_well.c
+++ b/drivers/gpu/drm/i915/display/intel_display_power_well.c
@@ -14,10 +14,13 @@
 #include "intel_crt.h"
 #include "intel_de.h"
 #include "intel_display_irq.h"
+#include "intel_display_limits.h"
 #include "intel_display_power_well.h"
 #include "intel_display_regs.h"
 #include "intel_display_rpm.h"
 #include "intel_display_types.h"
+#include "intel_display_utils.h"
+#include "intel_display_wa.h"
 #include "intel_dkl_phy.h"
 #include "intel_dkl_phy_regs.h"
 #include "intel_dmc.h"
@@ -194,6 +197,69 @@ int intel_power_well_refcount(struct i915_power_well *power_well)
 	return power_well->count;
 }
 
+static void clock_gating_dss_enable_disable(struct intel_display *display,
+					    u8 irq_pipe_mask,
+					    bool disable)
+{
+	struct drm_printer p;
+	enum pipe pipe;
+
+	switch (irq_pipe_mask) {
+	case BIT(PIPE_A):
+		pipe = PIPE_A;
+
+		if (disable)
+			intel_de_rmw(display, CLKGATE_DIS_DSSDSC,
+				     0, DSS_PIPE_A_GATING_DISABLED);
+		else
+			intel_de_rmw(display, CLKGATE_DIS_DSSDSC,
+				     DSS_PIPE_A_GATING_DISABLED, 0);
+		break;
+	case BIT(PIPE_B):
+		pipe = PIPE_B;
+
+		if (disable)
+			intel_de_rmw(display, CLKGATE_DIS_DSSDSC,
+				     0, DSS_PIPE_B_GATING_DISABLED);
+		else
+			intel_de_rmw(display, CLKGATE_DIS_DSSDSC,
+				     DSS_PIPE_B_GATING_DISABLED, 0);
+		break;
+	case BIT(PIPE_C):
+		pipe = PIPE_C;
+
+		if (disable)
+			intel_de_rmw(display, CLKGATE_DIS_DSSDSC,
+				     0, DSS_PIPE_C_GATING_DISABLED);
+		else
+			intel_de_rmw(display, CLKGATE_DIS_DSSDSC,
+				     DSS_PIPE_C_GATING_DISABLED, 0);
+		break;
+	case BIT(PIPE_D):
+		pipe = PIPE_D;
+
+		if (disable)
+			intel_de_rmw(display, CLKGATE_DIS_DSSDSC,
+				     0, DSS_PIPE_D_GATING_DISABLED);
+		else
+			intel_de_rmw(display, CLKGATE_DIS_DSSDSC,
+				     DSS_PIPE_D_GATING_DISABLED, 0);
+		break;
+	default:
+		MISSING_CASE(irq_pipe_mask);
+		break;
+	}
+
+	if (!drm_debug_enabled(DRM_UT_KMS))
+		return;
+
+	p = drm_dbg_printer(display->drm, DRM_UT_KMS, NULL);
+
+	drm_printf(&p, "dss clock gating %sd on pipe %c (0x%.8x)\n",
+		   str_enable_disable(!disable), pipe_name(pipe),
+		   intel_de_read(display, CLKGATE_DIS_DSSDSC));
+}
+
 /*
  * Starting with Haswell, we have a "Power Down Well" that can be turned off
  * when not needed anymore. We have 4 registers that can request the power well
@@ -203,15 +269,23 @@ int intel_power_well_refcount(struct i915_power_well *power_well)
 static void hsw_power_well_post_enable(struct intel_display *display,
 				       u8 irq_pipe_mask)
 {
-	if (irq_pipe_mask)
+	if (irq_pipe_mask) {
 		gen8_irq_power_well_post_enable(display, irq_pipe_mask);
+
+		if (intel_display_wa(display, 22021048059))
+			clock_gating_dss_enable_disable(display, irq_pipe_mask, false);
+	}
 }
 
 static void hsw_power_well_pre_disable(struct intel_display *display,
 				       u8 irq_pipe_mask)
 {
-	if (irq_pipe_mask)
+	if (irq_pipe_mask) {
+		if (intel_display_wa(display, 22021048059))
+			clock_gating_dss_enable_disable(display, irq_pipe_mask, true);
+
 		gen8_irq_power_well_pre_disable(display, irq_pipe_mask);
+	}
 }
 
 #define ICL_AUX_PW_TO_PHY(pw_idx)	\
diff --git a/drivers/gpu/drm/i915/display/intel_display_regs.h b/drivers/gpu/drm/i915/display/intel_display_regs.h
index 9e0d853f4b61..9740f32ced24 100644
--- a/drivers/gpu/drm/i915/display/intel_display_regs.h
+++ b/drivers/gpu/drm/i915/display/intel_display_regs.h
@@ -2211,6 +2211,13 @@
 #define   HSW_PWR_WELL_FORCE_ON			(1 << 19)
 #define HSW_PWR_WELL_CTL6			_MMIO(0x45414)
 
+/* clock gating DSS DSC disable register */
+#define CLKGATE_DIS_DSSDSC			_MMIO(0x46548)
+#define   DSS_PIPE_D_GATING_DISABLED		REG_BIT(31)
+#define   DSS_PIPE_C_GATING_DISABLED		REG_BIT(29)
+#define   DSS_PIPE_B_GATING_DISABLED		REG_BIT(27)
+#define   DSS_PIPE_A_GATING_DISABLED		REG_BIT(25)
+
 /* SKL Fuse Status */
 enum skl_power_gate {
 	SKL_PG0,
diff --git a/drivers/gpu/drm/i915/display/intel_display_wa.c b/drivers/gpu/drm/i915/display/intel_display_wa.c
index 86a6cc45b6ab..f8e14aa34dae 100644
--- a/drivers/gpu/drm/i915/display/intel_display_wa.c
+++ b/drivers/gpu/drm/i915/display/intel_display_wa.c
@@ -84,6 +84,8 @@ bool __intel_display_wa(struct intel_display *display, enum intel_display_wa wa,
 		return intel_display_needs_wa_16025573575(display);
 	case INTEL_DISPLAY_WA_22014263786:
 		return IS_DISPLAY_VERx100(display, 1100, 1400);
+	case INTEL_DISPLAY_WA_22021048059:
+		return DISPLAY_VER(display) >= 14;
 	default:
 		drm_WARN(display->drm, 1, "Missing Wa number: %s\n", name);
 		break;
diff --git a/drivers/gpu/drm/i915/display/intel_display_wa.h b/drivers/gpu/drm/i915/display/intel_display_wa.h
index 40f989f19df1..767420d5f406 100644
--- a/drivers/gpu/drm/i915/display/intel_display_wa.h
+++ b/drivers/gpu/drm/i915/display/intel_display_wa.h
@@ -34,6 +34,7 @@ enum intel_display_wa {
 	INTEL_DISPLAY_WA_16023588340,
 	INTEL_DISPLAY_WA_16025573575,
 	INTEL_DISPLAY_WA_22014263786,
+	INTEL_DISPLAY_WA_22021048059,
 };
 
 bool __intel_display_wa(struct intel_display *display, enum intel_display_wa wa, const char *name);
-- 
2.43.0


^ permalink raw reply related	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2026-01-30 10:03 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-01-28  7:48 [PATCH] drm/i915/power_well: Enable workaround for DSS clock gating issue (22021048059) Mika Kahola
2026-01-28 10:14 ` ✗ i915.CI.BAT: failure for " Patchwork
2026-01-28 10:36 ` [PATCH] " Jani Nikula
2026-01-30 10:02   ` Kahola, Mika
2026-01-29  3:11 ` Kandpal, Suraj
2026-01-30 10:03   ` Kahola, Mika

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