drm/panfrost: Display list of device JM contexts over debugfs

For DebugFS builds, create a filesystem knob that, for every single open
file of the Panfrost DRM device, shows its command name information and
PID (when applicable), and all of its existing JM contexts.

For every context, show the DRM scheduler priority value of all of its
scheduling entities.

Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Link: https://lore.kernel.org/r/20250917191859.500279-5-adrian.larumbe@collabora.com

diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c
index 69e72a800cd1e358ce8ee8e424542e1ccc665118..3af4b4753ca419e6d6422c9139038ba7f413294e 100644 (file)
--- a/drivers/gpu/drm/panfrost/panfrost_drv.c
+++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
@@ -716,6 +716,47 @@ static int panthor_gems_show(struct seq_file *m, void *data)
        return 0;
 }
 
+static void show_panfrost_jm_ctx(struct panfrost_jm_ctx *jm_ctx, u32 handle,
+                                struct seq_file *m)
+{
+       struct drm_device *ddev = ((struct drm_info_node *)m->private)->minor->dev;
+       const char *prio = "UNKNOWN";
+
+       static const char * const prios[] = {
+               [DRM_SCHED_PRIORITY_HIGH] = "HIGH",
+               [DRM_SCHED_PRIORITY_NORMAL] = "NORMAL",
+               [DRM_SCHED_PRIORITY_LOW] = "LOW",
+       };
+
+       if (jm_ctx->slot_entity[0].priority !=
+           jm_ctx->slot_entity[1].priority)
+               drm_warn(ddev, "Slot priorities should be the same in a single context");
+
+       if (jm_ctx->slot_entity[0].priority < ARRAY_SIZE(prios))
+               prio = prios[jm_ctx->slot_entity[0].priority];
+
+       seq_printf(m, " JM context %u: priority %s\n", handle, prio);
+}
+
+static int show_file_jm_ctxs(struct panfrost_file_priv *pfile,
+                            struct seq_file *m)
+{
+       struct panfrost_jm_ctx *jm_ctx;
+       unsigned long i;
+
+       xa_lock(&pfile->jm_ctxs);
+       xa_for_each(&pfile->jm_ctxs, i, jm_ctx) {
+               jm_ctx = panfrost_jm_ctx_get(jm_ctx);
+               xa_unlock(&pfile->jm_ctxs);
+               show_panfrost_jm_ctx(jm_ctx, i, m);
+               panfrost_jm_ctx_put(jm_ctx);
+               xa_lock(&pfile->jm_ctxs);
+       }
+       xa_unlock(&pfile->jm_ctxs);
+
+       return 0;
+}
+
 static struct drm_info_list panthor_debugfs_list[] = {
        {"gems", panthor_gems_show, 0, NULL},
 };
@@ -729,9 +770,64 @@ static int panthor_gems_debugfs_init(struct drm_minor *minor)
        return 0;
 }
 
+static int show_each_file(struct seq_file *m, void *arg)
+{
+       struct drm_info_node *node = (struct drm_info_node *)m->private;
+       struct drm_device *ddev = node->minor->dev;
+       int (*show)(struct panfrost_file_priv *, struct seq_file *) =
+               node->info_ent->data;
+       struct drm_file *file;
+       int ret;
+
+       ret = mutex_lock_interruptible(&ddev->filelist_mutex);
+       if (ret)
+               return ret;
+
+       list_for_each_entry(file, &ddev->filelist, lhead) {
+               struct task_struct *task;
+               struct panfrost_file_priv *pfile = file->driver_priv;
+               struct pid *pid;
+
+               /*
+                * Although we have a valid reference on file->pid, that does
+                * not guarantee that the task_struct who called get_pid() is
+                * still alive (e.g. get_pid(current) => fork() => exit()).
+                * Therefore, we need to protect this ->comm access using RCU.
+                */
+               rcu_read_lock();
+               pid = rcu_dereference(file->pid);
+               task = pid_task(pid, PIDTYPE_TGID);
+               seq_printf(m, "client_id %8llu pid %8d command %s:\n",
+                          file->client_id, pid_nr(pid),
+                          task ? task->comm : "<unknown>");
+               rcu_read_unlock();
+
+               ret = show(pfile, m);
+               if (ret < 0)
+                       break;
+
+               seq_puts(m, "\n");
+       }
+
+       mutex_unlock(&ddev->filelist_mutex);
+       return ret;
+}
+
+static struct drm_info_list panfrost_sched_debugfs_list[] = {
+       { "sched_ctxs", show_each_file, 0, show_file_jm_ctxs },
+};
+
+static void panfrost_sched_debugfs_init(struct drm_minor *minor)
+{
+       drm_debugfs_create_files(panfrost_sched_debugfs_list,
+                                ARRAY_SIZE(panfrost_sched_debugfs_list),
+                                minor->debugfs_root, minor);
+}
+
 static void panfrost_debugfs_init(struct drm_minor *minor)
 {
        panthor_gems_debugfs_init(minor);
+       panfrost_sched_debugfs_init(minor);
 }
 #endif