drm/i915/bmg: Read display register timeout

Log the address of the register that caused the timeout
interrupt by reading RMTIMEOUTREG_CAPTURE

--v2:
- Update RMTIMEOUTREG_CAPTURE naming (Suraj)

--v3:
- XeLpdp naming convention.
- Use if condition instead of else if

Signed-off-by: Mitul Golani <[e-mail]>
Reviewed-by: Suraj Kandpal <[e-mail]>
Signed-off-by: Suraj Kandpal <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

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

···
 			intel_pmdemand_irq_handler(dev_priv);
 			found = true;
 		}
+
+		if (iir & XELPDP_RM_TIMEOUT) {
+			u32 val = intel_uncore_read(&dev_priv->uncore,
+						    RM_TIMEOUT_REG_CAPTURE);
+			drm_warn(&dev_priv->drm, "Register Access Timeout = 0x%x\n", val);
+			found = true;
+		}
 	} else if (iir & GEN8_DE_MISC_GSE) {
 		intel_opregion_asle_intr(dev_priv);
 		found = true;
···
 
 	if (DISPLAY_VER(dev_priv) >= 14) {
 		de_misc_masked |= XELPDP_PMDEMAND_RSPTOUT_ERR |
-				  XELPDP_PMDEMAND_RSP;
+				  XELPDP_PMDEMAND_RSP | XELPDP_RM_TIMEOUT;
 	} else if (DISPLAY_VER(dev_priv) >= 11) {
 		enum port port;
 

drivers/gpu/drm/i915/i915_reg.h

···
 
 /* Display Internal Timeout Register */
 #define RM_TIMEOUT		_MMIO(0x42060)
+#define RM_TIMEOUT_REG_CAPTURE	_MMIO(0x420E0)
 #define  MMIO_TIMEOUT_US(us)	((us) << 0)
 
 /* interrupts */
···
 #define GEN8_DE_MISC_IMR _MMIO(0x44464)
 #define GEN8_DE_MISC_IIR _MMIO(0x44468)
 #define GEN8_DE_MISC_IER _MMIO(0x4446c)
+#define  XELPDP_RM_TIMEOUT		REG_BIT(29)
 #define  XELPDP_PMDEMAND_RSPTOUT_ERR	REG_BIT(27)
 #define  GEN8_DE_MISC_GSE		REG_BIT(27)
 #define  GEN8_DE_EDP_PSR		REG_BIT(19)