drm/i915/guc: reset GuC and retry on firmware load failure

Due to timing issues in the HW, some of the status bits required for GuC
authentication occasionally don't get set; when that happens, the GuC
cannot be initialized and we will be left with a wedged GPU. The W/A
suggested is to perform a soft reset of the GuC and attempt to reload
the F/W again for few times before giving up.

As the failure is dependent on timing, tests performed by triggering
manual full gpu reset (i915_wedged) showed that we could sometimes hit
this after several thousand iterations, but sometimes tests ran even
longer without any issues. Reset and reload mechanism proved helpful
when we indeed hit f/w load failure, so it is better to include this
to improve driver stability.

This change implements the following WAs,

	WaEnableuKernelHeaderValidFix:skl,bxt
	WaEnableGuCBootHashCheckNotSet:skl,bxt
Signed-off-by: Arun Siluvery <arun.siluvery@linux.intel.com>
Signed-off-by: Dave Gordon <david.s.gordon@intel.com>
Reviewed-by: Alex Dai <yu.dai@intel.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

drivers/gpu/drm/i915/i915_drv.h

@@ -2747,6 +2747,7 @@ extern long i915_compat_ioctl(struct file *filp, unsigned int cmd,
 extern int intel_gpu_reset(struct drm_device *dev, u32 engine_mask);
 extern bool intel_has_gpu_reset(struct drm_device *dev);
 extern int i915_reset(struct drm_device *dev);
+extern int intel_guc_reset(struct drm_i915_private *dev_priv);
 extern void intel_engine_init_hangcheck(struct intel_engine_cs *engine);
 extern unsigned long i915_chipset_val(struct drm_i915_private *dev_priv);
 extern unsigned long i915_mch_val(struct drm_i915_private *dev_priv);

drivers/gpu/drm/i915/i915_guc_reg.h

@@ -27,6 +27,7 @@
 /* Definitions of GuC H/W registers, bits, etc */
 
 #define GUC_STATUS			_MMIO(0xc000)
+#define   GS_MIA_IN_RESET		(1 << 0)
 #define   GS_BOOTROM_SHIFT		1
 #define   GS_BOOTROM_MASK		  (0x7F << GS_BOOTROM_SHIFT)
 #define   GS_BOOTROM_RSA_FAILED		  (0x50 << GS_BOOTROM_SHIFT)

drivers/gpu/drm/i915/i915_reg.h

@@ -165,6 +165,7 @@ static inline bool i915_mmio_reg_valid(i915_reg_t reg)
 #define  GEN6_GRDOM_MEDIA		(1 << 2)
 #define  GEN6_GRDOM_BLT			(1 << 3)
 #define  GEN6_GRDOM_VECS		(1 << 4)
+#define  GEN9_GRDOM_GUC			(1 << 5)
 #define  GEN8_GRDOM_MEDIA2		(1 << 7)
 
 #define RING_PP_DIR_BASE(ring)		_MMIO((ring)->mmio_base+0x228)

drivers/gpu/drm/i915/intel_guc_loader.c

@@ -353,6 +353,24 @@ static int guc_ucode_xfer(struct drm_i915_private *dev_priv)
 	return ret;
 }
 
+static int i915_reset_guc(struct drm_i915_private *dev_priv)
+{
+	int ret;
+	u32 guc_status;
+
+	ret = intel_guc_reset(dev_priv);
+	if (ret) {
+		DRM_ERROR("GuC reset failed, ret = %d\n", ret);
+		return ret;
+	}
+
+	guc_status = I915_READ(GUC_STATUS);
+	WARN(!(guc_status & GS_MIA_IN_RESET),
+	     "GuC status: 0x%x, MIA core expected to be in reset\n", guc_status);
+
+	return ret;
+}
+
 /**
  * intel_guc_ucode_load() - load GuC uCode into the device
  * @dev:	drm device
@@ -417,9 +435,36 @@ int intel_guc_ucode_load(struct drm_device *dev)
 	if (err)
 		goto fail;
 
+	/*
+	 * WaEnableuKernelHeaderValidFix:skl,bxt
+	 * For BXT, this is only upto B0 but below WA is required for later
+	 * steppings also so this is extended as well.
+	 */
+	/* WaEnableGuCBootHashCheckNotSet:skl,bxt */
 	err = guc_ucode_xfer(dev_priv);
+	if (err) {
+		int retries = 3;
+
+		DRM_ERROR("GuC fw load failed, err=%d, attempting reset and retry\n", err);
+
+		while (retries--) {
+			err = i915_reset_guc(dev_priv);
 			if (err)
+				break;
+
+			err = guc_ucode_xfer(dev_priv);
+			if (!err) {
+				DRM_DEBUG_DRIVER("GuC fw reload succeeded after reset\n");
+				break;
+			}
+			DRM_DEBUG_DRIVER("GuC fw reload retries left: %d\n", retries);
+		}
+
+		if (err) {
+			DRM_ERROR("GuC fw reload attempt failed, ret=%d\n", err);
 			goto fail;
+		}
+	}
 
 	guc_fw->guc_fw_load_status = GUC_FIRMWARE_SUCCESS;
 

drivers/gpu/drm/i915/intel_uncore.c

@@ -1673,6 +1673,25 @@ bool intel_has_gpu_reset(struct drm_device *dev)
 	return intel_get_gpu_reset(dev) != NULL;
 }
 
+int intel_guc_reset(struct drm_i915_private *dev_priv)
+{
+	int ret;
+	unsigned long irqflags;
+
+	if (!i915.enable_guc_submission)
+		return -EINVAL;
+
+	intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);
+	spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
+
+	ret = gen6_hw_domain_reset(dev_priv, GEN9_GRDOM_GUC);
+
+	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
+	intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
+
+	return ret;
+}
+
 bool intel_uncore_unclaimed_mmio(struct drm_i915_private *dev_priv)
 {
 	return check_for_unclaimed_mmio(dev_priv);