drm/i915: Implement Dbuf overlap detection feature starting from LNL

From LNL onwards there is a new hardware feature, which
allows to detect if the driver wrongly allocated DBuf
entries and they happen to overlap. If enabled this will
cause a specific interrupt to occur.
We now handle it in the driver, by writing correspondent
error message to kernel log.

v2: Initialize dbuf overlap flag in runtime_defaults (Jani Nikula)

v3: Unmask the overlap detection interrupt (Uma)

v4: use display over i915 (Jani Nikula)

v5: Use display instead of dev_priv (Jani Nikula)

v6: rebased to resolve merge conflicts

Bspec: 69450, 69464
Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
Signed-off-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
Reviewed-by: Mika Kahola <mika.kahola@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241030103319.207235-1-vinod.govindapillai@intel.com

drivers/gpu/drm/i915/display/intel_display_device.c

@@ -1314,6 +1314,7 @@ static const struct intel_display_device_info xe2_lpd_display = {
 	.__runtime_defaults.fbc_mask =
 		BIT(INTEL_FBC_A) | BIT(INTEL_FBC_B) |
 		BIT(INTEL_FBC_C) | BIT(INTEL_FBC_D),
+	.__runtime_defaults.has_dbuf_overlap_detection = true,
 };
 
 static const struct intel_display_device_info xe2_hpd_display = {
@@ -1784,6 +1785,10 @@ static void __intel_display_device_info_runtime_init(struct drm_i915_private *i9
 		if (IS_DISPLAY_VER(i915, 10, 12) &&
 		    (dfsm & GLK_DFSM_DISPLAY_DSC_DISABLE))
 			display_runtime->has_dsc = 0;
+
+		if (DISPLAY_VER(display) >= 20 &&
+		    (dfsm & XE2LPD_DFSM_DBUF_OVERLAP_DISABLE))
+			display_runtime->has_dbuf_overlap_detection = false;
 	}
 
 	if (DISPLAY_VER(i915) >= 20) {

drivers/gpu/drm/i915/display/intel_display_device.h

@@ -143,6 +143,7 @@ struct intel_display_platforms {
 #define HAS_CDCLK_SQUASH(i915)		(DISPLAY_INFO(i915)->has_cdclk_squash)
 #define HAS_CUR_FBC(i915)		(!HAS_GMCH(i915) && IS_DISPLAY_VER(i915, 7, 13))
 #define HAS_D12_PLANE_MINIMIZATION(i915) (IS_ROCKETLAKE(i915) || IS_ALDERLAKE_S(i915))
+#define HAS_DBUF_OVERLAP_DETECTION(__i915) (DISPLAY_RUNTIME_INFO(__i915)->has_dbuf_overlap_detection)
 #define HAS_DDI(i915)			(DISPLAY_INFO(i915)->has_ddi)
 #define HAS_DISPLAY(i915)		(DISPLAY_RUNTIME_INFO(i915)->pipe_mask != 0)
 #define HAS_DMC(i915)			(DISPLAY_RUNTIME_INFO(i915)->has_dmc)
@@ -248,6 +249,7 @@ struct intel_display_runtime_info {
 	bool has_dmc;
 	bool has_dsc;
 	bool edp_typec_support;
+	bool has_dbuf_overlap_detection;
 };
 
 struct intel_display_device_info {

drivers/gpu/drm/i915/display/intel_display_irq.c

@@ -903,6 +903,13 @@ gen8_de_misc_irq_handler(struct drm_i915_private *dev_priv, u32 iir)
 	struct intel_display *display = &dev_priv->display;
 	bool found = false;
 
+	if (HAS_DBUF_OVERLAP_DETECTION(display)) {
+		if (iir & XE2LPD_DBUF_OVERLAP_DETECTED) {
+			drm_warn(display->drm,  "DBuf overlap detected\n");
+			found = true;
+		}
+	}
+
 	if (DISPLAY_VER(dev_priv) >= 14) {
 		if (iir & (XELPDP_PMDEMAND_RSP |
 			   XELPDP_PMDEMAND_RSPTOUT_ERR)) {
@@ -1790,6 +1797,9 @@ void gen8_de_irq_postinstall(struct drm_i915_private *dev_priv)
 			de_port_masked |= DSI0_TE | DSI1_TE;
 	}
 
+	if (HAS_DBUF_OVERLAP_DETECTION(display))
+		de_misc_masked |= XE2LPD_DBUF_OVERLAP_DETECTED;
+
 	if (HAS_DSB(dev_priv))
 		de_pipe_masked |= GEN12_DSB_INT(INTEL_DSB_0) |
 			GEN12_DSB_INT(INTEL_DSB_1) |

drivers/gpu/drm/i915/i915_reg.h

@@ -2589,6 +2589,7 @@
 #define  GEN8_DE_MISC_GSE		REG_BIT(27)
 #define  GEN8_DE_EDP_PSR		REG_BIT(19)
 #define  XELPDP_PMDEMAND_RSP		REG_BIT(3)
+#define  XE2LPD_DBUF_OVERLAP_DETECTED	REG_BIT(1)
 
 #define GEN8_DE_MISC_IRQ_REGS		I915_IRQ_REGS(GEN8_DE_MISC_IMR, \
 						      GEN8_DE_MISC_IER, \
@@ -2895,6 +2896,7 @@
 #define   SKL_DFSM_PIPE_C_DISABLE	(1 << 28)
 #define   TGL_DFSM_PIPE_D_DISABLE	(1 << 22)
 #define   GLK_DFSM_DISPLAY_DSC_DISABLE	(1 << 7)
+#define   XE2LPD_DFSM_DBUF_OVERLAP_DISABLE	(1 << 3)
 
 #define XE2LPD_DE_CAP			_MMIO(0x41100)
 #define   XE2LPD_DE_CAP_3DLUT_MASK	REG_GENMASK(31, 30)