drm/i915: The return of i915_gpu_info to debugfs

Once upon a time before we had automated GPU state capture upon hangs,
we had intel_gpu_dump. Now we come almost full circle and reinstate that
view of the current GPU queues and registers by using the error capture
facility to snapshot the GPU state when debugfs/.../i915_gpu_info is
opened - which should provided useful debugging to both the error
capture routines (without having to cause a hang and avoid the error
state being eaten by igt) and generally.

v2: Rename drm_i915_error_state to i915_gpu_state to alleviate some name
collisions between the error state dump and inspecting the gpu state.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170214164611.11381-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_debugfs.c

@@ -988,89 +988,93 @@ static int i915_gem_fence_regs_info(struct seq_file *m, void *data)
 }
 
 #if IS_ENABLED(CONFIG_DRM_I915_CAPTURE_ERROR)
-
-static ssize_t
-i915_error_state_write(struct file *filp,
-		       const char __user *ubuf,
-		       size_t cnt,
-		       loff_t *ppos)
+static ssize_t gpu_state_read(struct file *file, char __user *ubuf,
+			      size_t count, loff_t *pos)
 {
-	struct i915_error_state_file_priv *error_priv = filp->private_data;
+	struct i915_gpu_state *error = file->private_data;
+	struct drm_i915_error_state_buf str;
+	ssize_t ret;
+	loff_t tmp;
 
-	DRM_DEBUG_DRIVER("Resetting error state\n");
-	i915_destroy_error_state(error_priv->i915);
-
-	return cnt;
-}
-
-static int i915_error_state_open(struct inode *inode, struct file *file)
-{
-	struct drm_i915_private *dev_priv = inode->i_private;
-	struct i915_error_state_file_priv *error_priv;
+	if (!error)
+		return 0;
 
-	error_priv = kzalloc(sizeof(*error_priv), GFP_KERNEL);
-	if (!error_priv)
-		return -ENOMEM;
+	ret = i915_error_state_buf_init(&str, error->i915, count, *pos);
+	if (ret)
+		return ret;
 
-	error_priv->i915 = dev_priv;
+	ret = i915_error_state_to_str(&str, error);
+	if (ret)
+		goto out;
 
-	i915_error_state_get(&dev_priv->drm, error_priv);
+	tmp = 0;
+	ret = simple_read_from_buffer(ubuf, count, &tmp, str.buf, str.bytes);
+	if (ret < 0)
+		goto out;
 
-	file->private_data = error_priv;
+	*pos = str.start + ret;
+out:
+	i915_error_state_buf_release(&str);
+	return ret;
+}
 
+static int gpu_state_release(struct inode *inode, struct file *file)
+{
+	i915_gpu_state_put(file->private_data);
 	return 0;
 }
 
-static int i915_error_state_release(struct inode *inode, struct file *file)
+static int i915_gpu_info_open(struct inode *inode, struct file *file)
 {
-	struct i915_error_state_file_priv *error_priv = file->private_data;
+	struct i915_gpu_state *gpu;
 
-	i915_error_state_put(error_priv);
-	kfree(error_priv);
+	gpu = i915_capture_gpu_state(inode->i_private);
+	if (!gpu)
+		return -ENOMEM;
 
+	file->private_data = gpu;
 	return 0;
 }
 
-static ssize_t i915_error_state_read(struct file *file, char __user *userbuf,
-				     size_t count, loff_t *pos)
+static const struct file_operations i915_gpu_info_fops = {
+	.owner = THIS_MODULE,
+	.open = i915_gpu_info_open,
+	.read = gpu_state_read,
+	.llseek = default_llseek,
+	.release = gpu_state_release,
+};
+
+static ssize_t
+i915_error_state_write(struct file *filp,
+		       const char __user *ubuf,
+		       size_t cnt,
+		       loff_t *ppos)
 {
-	struct i915_error_state_file_priv *error_priv = file->private_data;
-	struct drm_i915_error_state_buf error_str;
-	loff_t tmp_pos = 0;
-	ssize_t ret_count = 0;
-	int ret;
+	struct i915_gpu_state *error = filp->private_data;
 
-	ret = i915_error_state_buf_init(&error_str, error_priv->i915,
-					count, *pos);
-	if (ret)
-		return ret;
+	if (!error)
+		return 0;
 
-	ret = i915_error_state_to_str(&error_str, error_priv);
-	if (ret)
-		goto out;
+	DRM_DEBUG_DRIVER("Resetting error state\n");
+	i915_reset_error_state(error->i915);
 
-	ret_count = simple_read_from_buffer(userbuf, count, &tmp_pos,
-					    error_str.buf,
-					    error_str.bytes);
+	return cnt;
+}
 
-	if (ret_count < 0)
-		ret = ret_count;
-	else
-		*pos = error_str.start + ret_count;
-out:
-	i915_error_state_buf_release(&error_str);
-	return ret ?: ret_count;
+static int i915_error_state_open(struct inode *inode, struct file *file)
+{
+	file->private_data = i915_first_error_state(inode->i_private);
+	return 0;
 }
 
 static const struct file_operations i915_error_state_fops = {
 	.owner = THIS_MODULE,
 	.open = i915_error_state_open,
-	.read = i915_error_state_read,
+	.read = gpu_state_read,
 	.write = i915_error_state_write,
 	.llseek = default_llseek,
-	.release = i915_error_state_release,
+	.release = gpu_state_release,
 };
-
 #endif
 
 static int
@@ -4811,6 +4815,7 @@ static const struct i915_debugfs_files {
 	{"i915_gem_drop_caches", &i915_drop_caches_fops},
 #if IS_ENABLED(CONFIG_DRM_I915_CAPTURE_ERROR)
 	{"i915_error_state", &i915_error_state_fops},
+	{"i915_gpu_info", &i915_gpu_info_fops},
 #endif
 	{"i915_next_seqno", &i915_next_seqno_fops},
 	{"i915_display_crc_ctl", &i915_display_crc_ctl_fops},

drivers/gpu/drm/i915/i915_drv.c

@@ -1370,7 +1370,7 @@ void i915_driver_unload(struct drm_device *dev)
 
 	/* Free error state after interrupts are fully disabled. */
 	cancel_delayed_work_sync(&dev_priv->gpu_error.hangcheck_work);
-	i915_destroy_error_state(dev_priv);
+	i915_reset_error_state(dev_priv);
 
 	/* Flush any outstanding unpin_work. */
 	drain_workqueue(dev_priv->wq);

drivers/gpu/drm/i915/i915_drv.h

@@ -897,7 +897,7 @@ struct intel_device_info {
 
 struct intel_display_error_state;
 
-struct drm_i915_error_state {
+struct i915_gpu_state {
 	struct kref ref;
 	struct timeval time;
 	struct timeval boottime;
@@ -917,7 +917,7 @@ struct drm_i915_error_state {
 	u32 eir;
 	u32 pgtbl_er;
 	u32 ier;
-	u32 gtier[4];
+	u32 gtier[4], ngtier;
 	u32 ccid;
 	u32 derrmr;
 	u32 forcewake;
@@ -931,6 +931,7 @@ struct drm_i915_error_state {
 	u32 gab_ctl;
 	u32 gfx_mode;
 
+	u32 nfence;
 	u64 fence[I915_MAX_NUM_FENCES];
 	struct intel_overlay_error_state *overlay;
 	struct intel_display_error_state *display;
@@ -1512,11 +1513,6 @@ struct drm_i915_error_state_buf {
 	loff_t pos;
 };
 
-struct i915_error_state_file_priv {
-	struct drm_i915_private *i915;
-	struct drm_i915_error_state *error;
-};
-
 #define I915_RESET_TIMEOUT (10 * HZ) /* 10s */
 #define I915_FENCE_TIMEOUT (10 * HZ) /* 10s */
 
@@ -1533,7 +1529,7 @@ struct i915_gpu_error {
 	/* For reset and error_state handling. */
 	spinlock_t lock;
 	/* Protected by the above dev->gpu_error.lock. */
-	struct drm_i915_error_state *first_error;
+	struct i915_gpu_state *first_error;
 
 	unsigned long missed_irq_rings;
 
@@ -3574,7 +3570,7 @@ static inline void intel_display_crc_init(struct drm_i915_private *dev_priv) {}
 __printf(2, 3)
 void i915_error_printf(struct drm_i915_error_state_buf *e, const char *f, ...);
 int i915_error_state_to_str(struct drm_i915_error_state_buf *estr,
-			    const struct i915_error_state_file_priv *error);
+			    const struct i915_gpu_state *gpu);
 int i915_error_state_buf_init(struct drm_i915_error_state_buf *eb,
 			      struct drm_i915_private *i915,
 			      size_t count, loff_t pos);
@@ -3583,13 +3579,28 @@ static inline void i915_error_state_buf_release(
 {
 	kfree(eb->buf);
 }
+
+struct i915_gpu_state *i915_capture_gpu_state(struct drm_i915_private *i915);
 void i915_capture_error_state(struct drm_i915_private *dev_priv,
 			      u32 engine_mask,
 			      const char *error_msg);
-void i915_error_state_get(struct drm_device *dev,
-			  struct i915_error_state_file_priv *error_priv);
-void i915_error_state_put(struct i915_error_state_file_priv *error_priv);
-void i915_destroy_error_state(struct drm_i915_private *dev_priv);
+
+static inline struct i915_gpu_state *
+i915_gpu_state_get(struct i915_gpu_state *gpu)
+{
+	kref_get(&gpu->ref);
+	return gpu;
+}
+
+void __i915_gpu_state_free(struct kref *kref);
+static inline void i915_gpu_state_put(struct i915_gpu_state *gpu)
+{
+	if (gpu)
+		kref_put(&gpu->ref, __i915_gpu_state_free);
+}
+
+struct i915_gpu_state *i915_first_error_state(struct drm_i915_private *i915);
+void i915_reset_error_state(struct drm_i915_private *i915);
 
 #else
 
@@ -3599,7 +3610,13 @@ static inline void i915_capture_error_state(struct drm_i915_private *dev_priv,
 {
 }
 
-static inline void i915_destroy_error_state(struct drm_i915_private *dev_priv)
+static inline struct i915_gpu_state *
+i915_first_error_state(struct drm_i915_private *i915)
+{
+	return NULL;
+}
+
+static inline void i915_reset_error_state(struct drm_i915_private *i915)
 {
 }
 
@@ -3747,7 +3764,6 @@ extern void intel_overlay_print_error_state(struct drm_i915_error_state_buf *e,
 extern struct intel_display_error_state *
 intel_display_capture_error_state(struct drm_i915_private *dev_priv);
 extern void intel_display_print_error_state(struct drm_i915_error_state_buf *e,
-					    struct drm_i915_private *dev_priv,
 					    struct intel_display_error_state *error);
 
 int sandybridge_pcode_read(struct drm_i915_private *dev_priv, u32 mbox, u32 *val);

drivers/gpu/drm/i915/i915_gpu_error.c

@@ -342,7 +342,7 @@ static void print_error_buffers(struct drm_i915_error_state_buf *m,
 }
 
 static void error_print_instdone(struct drm_i915_error_state_buf *m,
-				 struct drm_i915_error_engine *ee)
+				 const struct drm_i915_error_engine *ee)
 {
 	int slice;
 	int subslice;
@@ -372,7 +372,7 @@ static void error_print_instdone(struct drm_i915_error_state_buf *m,
 
 static void error_print_request(struct drm_i915_error_state_buf *m,
 				const char *prefix,
-				struct drm_i915_error_request *erq)
+				const struct drm_i915_error_request *erq)
 {
 	if (!erq->seqno)
 		return;
@@ -386,7 +386,7 @@ static void error_print_request(struct drm_i915_error_state_buf *m,
 
 static void error_print_context(struct drm_i915_error_state_buf *m,
 				const char *header,
-				struct drm_i915_error_context *ctx)
+				const struct drm_i915_error_context *ctx)
 {
 	err_printf(m, "%s%s[%d] user_handle %d hw_id %d, ban score %d guilty %d active %d\n",
 		   header, ctx->comm, ctx->pid, ctx->handle, ctx->hw_id,
@@ -394,7 +394,7 @@ static void error_print_context(struct drm_i915_error_state_buf *m,
 }
 
 static void error_print_engine(struct drm_i915_error_state_buf *m,
-			       struct drm_i915_error_engine *ee)
+			       const struct drm_i915_error_engine *ee)
 {
 	err_printf(m, "%s command stream:\n", engine_str(ee->engine_id));
 	err_printf(m, "  START: 0x%08x\n", ee->start);
@@ -569,20 +569,31 @@ static void err_print_params(struct drm_i915_error_state_buf *m,
 #undef PRINT
 }
 
+static void err_print_pciid(struct drm_i915_error_state_buf *m,
+			    struct drm_i915_private *i915)
+{
+	struct pci_dev *pdev = i915->drm.pdev;
+
+	err_printf(m, "PCI ID: 0x%04x\n", pdev->device);
+	err_printf(m, "PCI Revision: 0x%02x\n", pdev->revision);
+	err_printf(m, "PCI Subsystem: %04x:%04x\n",
+		   pdev->subsystem_vendor,
+		   pdev->subsystem_device);
+}
+
 int i915_error_state_to_str(struct drm_i915_error_state_buf *m,
-			    const struct i915_error_state_file_priv *error_priv)
+			    const struct i915_gpu_state *error)
 {
-	struct drm_i915_private *dev_priv = error_priv->i915;
-	struct pci_dev *pdev = dev_priv->drm.pdev;
-	struct drm_i915_error_state *error = error_priv->error;
+	struct drm_i915_private *dev_priv = m->i915;
 	struct drm_i915_error_object *obj;
 	int i, j;
 
 	if (!error) {
-		err_printf(m, "no error state collected\n");
-		goto out;
+		err_printf(m, "No error state collected\n");
+		return 0;
 	}
 
+	if (*error->error_msg)
 		err_printf(m, "%s\n", error->error_msg);
 	err_printf(m, "Kernel: " UTS_RELEASE "\n");
 	err_printf(m, "Time: %ld s %ld us\n",
@@ -605,11 +616,7 @@ int i915_error_state_to_str(struct drm_i915_error_state_buf *m,
 	err_printf(m, "Reset count: %u\n", error->reset_count);
 	err_printf(m, "Suspend count: %u\n", error->suspend_count);
 	err_printf(m, "Platform: %s\n", intel_platform_name(error->device_info.platform));
-	err_printf(m, "PCI ID: 0x%04x\n", pdev->device);
-	err_printf(m, "PCI Revision: 0x%02x\n", pdev->revision);
-	err_printf(m, "PCI Subsystem: %04x:%04x\n",
-		   pdev->subsystem_vendor,
-		   pdev->subsystem_device);
+	err_print_pciid(m, error->i915);
 
 	err_printf(m, "IOMMU enabled?: %d\n", error->iommu);
 
@@ -625,19 +632,15 @@ int i915_error_state_to_str(struct drm_i915_error_state_buf *m,
 
 	err_printf(m, "EIR: 0x%08x\n", error->eir);
 	err_printf(m, "IER: 0x%08x\n", error->ier);
-	if (INTEL_GEN(dev_priv) >= 8) {
-		for (i = 0; i < 4; i++)
-			err_printf(m, "GTIER gt %d: 0x%08x\n", i,
-				   error->gtier[i]);
-	} else if (HAS_PCH_SPLIT(dev_priv) || IS_VALLEYVIEW(dev_priv))
-		err_printf(m, "GTIER: 0x%08x\n", error->gtier[0]);
+	for (i = 0; i < error->ngtier; i++)
+		err_printf(m, "GTIER[%d]: 0x%08x\n", i, error->gtier[i]);
 	err_printf(m, "PGTBL_ER: 0x%08x\n", error->pgtbl_er);
 	err_printf(m, "FORCEWAKE: 0x%08x\n", error->forcewake);
 	err_printf(m, "DERRMR: 0x%08x\n", error->derrmr);
 	err_printf(m, "CCID: 0x%08x\n", error->ccid);
 	err_printf(m, "Missed interrupts: 0x%08lx\n", dev_priv->gpu_error.missed_irq_rings);
 
-	for (i = 0; i < dev_priv->num_fence_regs; i++)
+	for (i = 0; i < error->nfence; i++)
 		err_printf(m, "  fence[%d] = %08llx\n", i, error->fence[i]);
 
 	if (INTEL_GEN(dev_priv) >= 6) {
@@ -686,7 +689,7 @@ int i915_error_state_to_str(struct drm_i915_error_state_buf *m,
 			    error->pinned_bo_count);
 
 	for (i = 0; i < ARRAY_SIZE(error->engine); i++) {
-		struct drm_i915_error_engine *ee = &error->engine[i];
+		const struct drm_i915_error_engine *ee = &error->engine[i];
 
 		obj = ee->batchbuffer;
 		if (obj) {
@@ -751,12 +754,11 @@ int i915_error_state_to_str(struct drm_i915_error_state_buf *m,
 		intel_overlay_print_error_state(m, error->overlay);
 
 	if (error->display)
-		intel_display_print_error_state(m, dev_priv, error->display);
+		intel_display_print_error_state(m, error->display);
 
 	err_print_capabilities(m, &error->device_info);
 	err_print_params(m, &error->params);
 
-out:
 	if (m->bytes == 0 && m->err)
 		return m->err;
 
@@ -808,10 +810,10 @@ static void i915_error_object_free(struct drm_i915_error_object *obj)
 	kfree(obj);
 }
 
-static void i915_error_state_free(struct kref *error_ref)
+void __i915_gpu_state_free(struct kref *error_ref)
 {
-	struct drm_i915_error_state *error = container_of(error_ref,
-							  typeof(*error), ref);
+	struct i915_gpu_state *error =
+		container_of(error_ref, typeof(*error), ref);
 	int i;
 
 	for (i = 0; i < ARRAY_SIZE(error->engine); i++) {
@@ -976,7 +978,7 @@ static u32 capture_error_bo(struct drm_i915_error_buffer *err,
  * It's only a small step better than a random number in its current form.
  */
 static uint32_t i915_error_generate_code(struct drm_i915_private *dev_priv,
-					 struct drm_i915_error_state *error,
+					 struct i915_gpu_state *error,
 					 int *engine_id)
 {
 	uint32_t error_code = 0;
@@ -1001,20 +1003,21 @@ static uint32_t i915_error_generate_code(struct drm_i915_private *dev_priv,
 }
 
 static void i915_gem_record_fences(struct drm_i915_private *dev_priv,
-				   struct drm_i915_error_state *error)
+				   struct i915_gpu_state *error)
 {
 	int i;
 
-	if (IS_GEN3(dev_priv) || IS_GEN2(dev_priv)) {
+	if (INTEL_GEN(dev_priv) >= 6) {
 		for (i = 0; i < dev_priv->num_fence_regs; i++)
-			error->fence[i] = I915_READ(FENCE_REG(i));
-	} else if (IS_GEN5(dev_priv) || IS_GEN4(dev_priv)) {
+			error->fence[i] = I915_READ64(FENCE_REG_GEN6_LO(i));
+	} else if (INTEL_GEN(dev_priv) >= 4) {
 		for (i = 0; i < dev_priv->num_fence_regs; i++)
 			error->fence[i] = I915_READ64(FENCE_REG_965_LO(i));
-	} else if (INTEL_GEN(dev_priv) >= 6) {
+	} else {
 		for (i = 0; i < dev_priv->num_fence_regs; i++)
-			error->fence[i] = I915_READ64(FENCE_REG_GEN6_LO(i));
+			error->fence[i] = I915_READ(FENCE_REG(i));
 	}
+	error->nfence = i;
 }
 
 static inline u32
@@ -1038,7 +1041,7 @@ gen8_engine_sync_index(struct intel_engine_cs *engine,
 	return idx;
 }
 
-static void gen8_record_semaphore_state(struct drm_i915_error_state *error,
+static void gen8_record_semaphore_state(struct i915_gpu_state *error,
 					struct intel_engine_cs *engine,
 					struct drm_i915_error_engine *ee)
 {
@@ -1131,7 +1134,7 @@ static void error_record_engine_waiters(struct intel_engine_cs *engine,
 	spin_unlock_irq(&b->lock);
 }
 
-static void error_record_engine_registers(struct drm_i915_error_state *error,
+static void error_record_engine_registers(struct i915_gpu_state *error,
 					  struct intel_engine_cs *engine,
 					  struct drm_i915_error_engine *ee)
 {
@@ -1328,7 +1331,7 @@ static void record_context(struct drm_i915_error_context *e,
 }
 
 static void i915_gem_record_rings(struct drm_i915_private *dev_priv,
-				  struct drm_i915_error_state *error)
+				  struct i915_gpu_state *error)
 {
 	struct i915_ggtt *ggtt = &dev_priv->ggtt;
 	int i;
@@ -1404,7 +1407,7 @@ static void i915_gem_record_rings(struct drm_i915_private *dev_priv,
 }
 
 static void i915_gem_capture_vm(struct drm_i915_private *dev_priv,
-				struct drm_i915_error_state *error,
+				struct i915_gpu_state *error,
 				struct i915_address_space *vm,
 				int idx)
 {
@@ -1430,7 +1433,7 @@ static void i915_gem_capture_vm(struct drm_i915_private *dev_priv,
 }
 
 static void i915_capture_active_buffers(struct drm_i915_private *dev_priv,
-					struct drm_i915_error_state *error)
+					struct i915_gpu_state *error)
 {
 	int cnt = 0, i, j;
 
@@ -1455,7 +1458,7 @@ static void i915_capture_active_buffers(struct drm_i915_private *dev_priv,
 }
 
 static void i915_capture_pinned_buffers(struct drm_i915_private *dev_priv,
-					struct drm_i915_error_state *error)
+					struct i915_gpu_state *error)
 {
 	struct i915_address_space *vm = &dev_priv->ggtt.base;
 	struct drm_i915_error_buffer *bo;
@@ -1486,7 +1489,7 @@ static void i915_capture_pinned_buffers(struct drm_i915_private *dev_priv,
 }
 
 static void i915_gem_capture_guc_log_buffer(struct drm_i915_private *dev_priv,
-					    struct drm_i915_error_state *error)
+					    struct i915_gpu_state *error)
 {
 	/* Capturing log buf contents won't be useful if logging was disabled */
 	if (!dev_priv->guc.log.vma || (i915.guc_log_level < 0))
@@ -1498,7 +1501,7 @@ static void i915_gem_capture_guc_log_buffer(struct drm_i915_private *dev_priv,
 
 /* Capture all registers which don't fit into another category. */
 static void i915_capture_reg_state(struct drm_i915_private *dev_priv,
-				   struct drm_i915_error_state *error)
+				   struct i915_gpu_state *error)
 {
 	int i;
 
@@ -1555,9 +1558,11 @@ static void i915_capture_reg_state(struct drm_i915_private *dev_priv,
 		error->ier = I915_READ(GEN8_DE_MISC_IER);
 		for (i = 0; i < 4; i++)
 			error->gtier[i] = I915_READ(GEN8_GT_IER(i));
+		error->ngtier = 4;
 	} else if (HAS_PCH_SPLIT(dev_priv)) {
 		error->ier = I915_READ(DEIER);
 		error->gtier[0] = I915_READ(GTIER);
+		error->ngtier = 1;
 	} else if (IS_GEN2(dev_priv)) {
 		error->ier = I915_READ16(IER);
 	} else if (!IS_VALLEYVIEW(dev_priv)) {
@@ -1568,7 +1573,7 @@ static void i915_capture_reg_state(struct drm_i915_private *dev_priv,
 }
 
 static void i915_error_capture_msg(struct drm_i915_private *dev_priv,
-				   struct drm_i915_error_state *error,
+				   struct i915_gpu_state *error,
 				   u32 engine_mask,
 				   const char *error_msg)
 {
@@ -1595,7 +1600,7 @@ static void i915_error_capture_msg(struct drm_i915_private *dev_priv,
 }
 
 static void i915_capture_gen_state(struct drm_i915_private *dev_priv,
-				   struct drm_i915_error_state *error)
+				   struct i915_gpu_state *error)
 {
 	error->iommu = -1;
 #ifdef CONFIG_INTEL_IOMMU
@@ -1611,7 +1616,7 @@ static void i915_capture_gen_state(struct drm_i915_private *dev_priv,
 
 static int capture(void *data)
 {
-	struct drm_i915_error_state *error = data;
+	struct i915_gpu_state *error = data;
 
 	do_gettimeofday(&error->time);
 	error->boottime = ktime_to_timeval(ktime_get_boottime());
@@ -1637,6 +1642,23 @@ static int capture(void *data)
 
 #define DAY_AS_SECONDS(x) (24 * 60 * 60 * (x))
 
+struct i915_gpu_state *
+i915_capture_gpu_state(struct drm_i915_private *i915)
+{
+	struct i915_gpu_state *error;
+
+	error = kzalloc(sizeof(*error), GFP_ATOMIC);
+	if (!error)
+		return NULL;
+
+	kref_init(&error->ref);
+	error->i915 = i915;
+
+	stop_machine(capture, error, NULL);
+
+	return error;
+}
+
 /**
  * i915_capture_error_state - capture an error record for later analysis
  * @dev: drm device
@@ -1651,7 +1673,7 @@ void i915_capture_error_state(struct drm_i915_private *dev_priv,
 			      const char *error_msg)
 {
 	static bool warned;
-	struct drm_i915_error_state *error;
+	struct i915_gpu_state *error;
 	unsigned long flags;
 
 	if (!i915.error_capture)
@@ -1660,18 +1682,12 @@ void i915_capture_error_state(struct drm_i915_private *dev_priv,
 	if (READ_ONCE(dev_priv->gpu_error.first_error))
 		return;
 
-	/* Account for pipe specific data like PIPE*STAT */
-	error = kzalloc(sizeof(*error), GFP_ATOMIC);
+	error = i915_capture_gpu_state(dev_priv);
 	if (!error) {
 		DRM_DEBUG_DRIVER("out of memory, not capturing error state\n");
 		return;
 	}
 
-	kref_init(&error->ref);
-	error->i915 = dev_priv;
-
-	stop_machine(capture, error, NULL);
-
 	i915_error_capture_msg(dev_priv, error, engine_mask, error_msg);
 	DRM_INFO("%s\n", error->error_msg);
 
@@ -1685,7 +1701,7 @@ void i915_capture_error_state(struct drm_i915_private *dev_priv,
 	}
 
 	if (error) {
-		i915_error_state_free(&error->ref);
+		__i915_gpu_state_free(&error->ref);
 		return;
 	}
 
@@ -1701,33 +1717,28 @@ void i915_capture_error_state(struct drm_i915_private *dev_priv,
 	}
 }
 
-void i915_error_state_get(struct drm_device *dev,
-			  struct i915_error_state_file_priv *error_priv)
+struct i915_gpu_state *
+i915_first_error_state(struct drm_i915_private *i915)
 {
-	struct drm_i915_private *dev_priv = to_i915(dev);
+	struct i915_gpu_state *error;
 
-	spin_lock_irq(&dev_priv->gpu_error.lock);
-	error_priv->error = dev_priv->gpu_error.first_error;
-	if (error_priv->error)
-		kref_get(&error_priv->error->ref);
-	spin_unlock_irq(&dev_priv->gpu_error.lock);
-}
+	spin_lock_irq(&i915->gpu_error.lock);
+	error = i915->gpu_error.first_error;
+	if (error)
+		i915_gpu_state_get(error);
+	spin_unlock_irq(&i915->gpu_error.lock);
 
-void i915_error_state_put(struct i915_error_state_file_priv *error_priv)
-{
-	if (error_priv->error)
-		kref_put(&error_priv->error->ref, i915_error_state_free);
+	return error;
 }
 
-void i915_destroy_error_state(struct drm_i915_private *dev_priv)
+void i915_reset_error_state(struct drm_i915_private *i915)
 {
-	struct drm_i915_error_state *error;
+	struct i915_gpu_state *error;
 
-	spin_lock_irq(&dev_priv->gpu_error.lock);
-	error = dev_priv->gpu_error.first_error;
-	dev_priv->gpu_error.first_error = NULL;
-	spin_unlock_irq(&dev_priv->gpu_error.lock);
+	spin_lock_irq(&i915->gpu_error.lock);
+	error = i915->gpu_error.first_error;
+	i915->gpu_error.first_error = NULL;
+	spin_unlock_irq(&i915->gpu_error.lock);
 
-	if (error)
-		kref_put(&error->ref, i915_error_state_free);
+	i915_gpu_state_put(error);
 }

drivers/gpu/drm/i915/i915_sysfs.c

@@ -522,33 +522,27 @@ static ssize_t error_state_read(struct file *filp, struct kobject *kobj,
 
 	struct device *kdev = kobj_to_dev(kobj);
 	struct drm_i915_private *dev_priv = kdev_minor_to_i915(kdev);
-	struct drm_device *dev = &dev_priv->drm;
-	struct i915_error_state_file_priv error_priv;
 	struct drm_i915_error_state_buf error_str;
-	ssize_t ret_count = 0;
-	int ret;
-
-	memset(&error_priv, 0, sizeof(error_priv));
+	struct i915_gpu_state *gpu;
+	ssize_t ret;
 
-	ret = i915_error_state_buf_init(&error_str, to_i915(dev), count, off);
+	ret = i915_error_state_buf_init(&error_str, dev_priv, count, off);
 	if (ret)
 		return ret;
 
-	error_priv.i915 = dev_priv;
-	i915_error_state_get(dev, &error_priv);
-
-	ret = i915_error_state_to_str(&error_str, &error_priv);
+	gpu = i915_first_error_state(dev_priv);
+	ret = i915_error_state_to_str(&error_str, gpu);
 	if (ret)
 		goto out;
 
-	ret_count = count < error_str.bytes ? count : error_str.bytes;
+	ret = count < error_str.bytes ? count : error_str.bytes;
+	memcpy(buf, error_str.buf, ret);
 
-	memcpy(buf, error_str.buf, ret_count);
 out:
-	i915_error_state_put(&error_priv);
+	i915_gpu_state_put(gpu);
 	i915_error_state_buf_release(&error_str);
 
-	return ret ?: ret_count;
+	return ret;
 }
 
 static ssize_t error_state_write(struct file *file, struct kobject *kobj,
@@ -559,7 +553,7 @@ static ssize_t error_state_write(struct file *file, struct kobject *kobj,
 	struct drm_i915_private *dev_priv = kdev_minor_to_i915(kdev);
 
 	DRM_DEBUG_DRIVER("Resetting error state\n");
-	i915_destroy_error_state(dev_priv);
+	i915_reset_error_state(dev_priv);
 
 	return count;
 }

drivers/gpu/drm/i915/intel_display.c

@@ -15838,9 +15838,9 @@ intel_display_capture_error_state(struct drm_i915_private *dev_priv)
 
 void
 intel_display_print_error_state(struct drm_i915_error_state_buf *m,
-				struct drm_i915_private *dev_priv,
 				struct intel_display_error_state *error)
 {
+	struct drm_i915_private *dev_priv = m->i915;
 	int i;
 
 	if (!error)