drm/v3d: Add parameter to retrieve the global number of GPU resets

The GL extension KHR_robustness uses the number of global and per-context
GPU resets to learn about graphics resets that affect a GL context. This
commit introduces a new V3D parameter to retrieve the global number of
GPU resets that have happened since the driver was probed.

To retrieve this information, user-space must use DRM_V3D_PARAM_GLOBAL_RESET_COUNTER.

Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
Link: https://lore.kernel.org/r/20250711-v3d-reset-counter-v1-1-1ac73e9fca2d@igalia.com
Signed-off-by: Maíra Canal <mcanal@igalia.com>

drivers/gpu/drm/v3d/v3d_drv.c

@@ -107,6 +107,11 @@ static int v3d_get_param_ioctl(struct drm_device *dev, void *data,
 	case DRM_V3D_PARAM_SUPPORTS_SUPER_PAGES:
 		args->value = !!v3d->gemfs;
 		return 0;
+	case DRM_V3D_PARAM_GLOBAL_RESET_COUNTER:
+		mutex_lock(&v3d->reset_lock);
+		args->value = v3d->reset_counter;
+		mutex_unlock(&v3d->reset_lock);
+		return 0;
 	default:
 		DRM_DEBUG("Unknown parameter %d\n", args->param);
 		return -EINVAL;

drivers/gpu/drm/v3d/v3d_drv.h

@@ -196,6 +196,11 @@ struct v3d_dev {
 	 * all jobs.
 	 */
 	struct v3d_perfmon *global_perfmon;
+
+	/* Global reset counter. The counter must be incremented when
+	 * a GPU reset happens. It must be protected by @reset_lock.
+	 */
+	unsigned int reset_counter;
 };
 
 static inline struct v3d_dev *

drivers/gpu/drm/v3d/v3d_sched.c

@@ -731,6 +731,8 @@ v3d_gpu_reset_for_timeout(struct v3d_dev *v3d, struct drm_sched_job *sched_job)
 	/* get the GPU back into the init state */
 	v3d_reset(v3d);
 
+	v3d->reset_counter++;
+
 	for (q = 0; q < V3D_MAX_QUEUES; q++)
 		drm_sched_resubmit_jobs(&v3d->queue[q].sched);
 

include/uapi/drm/v3d_drm.h

@@ -294,6 +294,7 @@ enum drm_v3d_param {
 	DRM_V3D_PARAM_SUPPORTS_CPU_QUEUE,
 	DRM_V3D_PARAM_MAX_PERF_COUNTERS,
 	DRM_V3D_PARAM_SUPPORTS_SUPER_PAGES,
+	DRM_V3D_PARAM_GLOBAL_RESET_COUNTER,
 };
 
 struct drm_v3d_get_param {