drm/client: Move suspend/resume into DRM client callbacks

Suspend and resume is still tied to fbdev emulation. Modeset helpers
and several drivers call drm_fb_helper_set_suspend_unlocked() to inform
the fbdev client about suspend/resume events.

To make it work with arbitrary clients, add per-client callback
functions for suspend and resume. Implement them for fbdev emulation
with the existing drm_fb_helper_set_suspend_unlocked(). Then update
DRM's modeset helpers to call the new interface.

Clients that are not fbdev can now implement suspend/resume to their
requirements.

The callback parameter holds_console_lock is a workaround for i915,
radeon and xe, which possibly call the interface while having the
console lock acquired. Even though the commit doesn't modify these
drivers, it already adds the flag to avoid churn later on. New code
should not hold the console lock.

v4:
- clarify holds_console_lock in commit description (Jonathan)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241014085740.582287-8-tzimmermann@suse.de

drivers/gpu/drm/drm_client_event.c

@@ -107,6 +107,66 @@ void drm_client_dev_restore(struct drm_device *dev)
 	mutex_unlock(&dev->clientlist_mutex);
 }
 
+static int drm_client_suspend(struct drm_client_dev *client, bool holds_console_lock)
+{
+	struct drm_device *dev = client->dev;
+	int ret = 0;
+
+	if (drm_WARN_ON_ONCE(dev, client->suspended))
+		return 0;
+
+	if (client->funcs && client->funcs->suspend)
+		ret = client->funcs->suspend(client, holds_console_lock);
+	drm_dbg_kms(dev, "%s: ret=%d\n", client->name, ret);
+
+	client->suspended = true;
+
+	return ret;
+}
+
+void drm_client_dev_suspend(struct drm_device *dev, bool holds_console_lock)
+{
+	struct drm_client_dev *client;
+
+	mutex_lock(&dev->clientlist_mutex);
+	list_for_each_entry(client, &dev->clientlist, list) {
+		if (!client->suspended)
+			drm_client_suspend(client, holds_console_lock);
+	}
+	mutex_unlock(&dev->clientlist_mutex);
+}
+EXPORT_SYMBOL(drm_client_dev_suspend);
+
+static int drm_client_resume(struct drm_client_dev *client, bool holds_console_lock)
+{
+	struct drm_device *dev = client->dev;
+	int ret = 0;
+
+	if (drm_WARN_ON_ONCE(dev, !client->suspended))
+		return 0;
+
+	if (client->funcs && client->funcs->resume)
+		ret = client->funcs->resume(client, holds_console_lock);
+	drm_dbg_kms(dev, "%s: ret=%d\n", client->name, ret);
+
+	client->suspended = false;
+
+	return ret;
+}
+
+void drm_client_dev_resume(struct drm_device *dev, bool holds_console_lock)
+{
+	struct drm_client_dev *client;
+
+	mutex_lock(&dev->clientlist_mutex);
+	list_for_each_entry(client, &dev->clientlist, list) {
+		if  (client->suspended)
+			drm_client_resume(client, holds_console_lock);
+	}
+	mutex_unlock(&dev->clientlist_mutex);
+}
+EXPORT_SYMBOL(drm_client_dev_resume);
+
 #ifdef CONFIG_DEBUG_FS
 static int drm_client_debugfs_internal_clients(struct seq_file *m, void *data)
 {

drivers/gpu/drm/drm_fbdev_client.c

@@ -61,11 +61,37 @@ static int drm_fbdev_client_hotplug(struct drm_client_dev *client)
 	return ret;
 }
 
+static int drm_fbdev_client_suspend(struct drm_client_dev *client, bool holds_console_lock)
+{
+	struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
+
+	if (holds_console_lock)
+		drm_fb_helper_set_suspend(fb_helper, true);
+	else
+		drm_fb_helper_set_suspend_unlocked(fb_helper, true);
+
+	return 0;
+}
+
+static int drm_fbdev_client_resume(struct drm_client_dev *client, bool holds_console_lock)
+{
+	struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
+
+	if (holds_console_lock)
+		drm_fb_helper_set_suspend(fb_helper, false);
+	else
+		drm_fb_helper_set_suspend_unlocked(fb_helper, false);
+
+	return 0;
+}
+
 static const struct drm_client_funcs drm_fbdev_client_funcs = {
 	.owner		= THIS_MODULE,
 	.unregister	= drm_fbdev_client_unregister,
 	.restore	= drm_fbdev_client_restore,
 	.hotplug	= drm_fbdev_client_hotplug,
+	.suspend	= drm_fbdev_client_suspend,
+	.resume		= drm_fbdev_client_resume,
 };
 
 /**
@@ -76,8 +102,8 @@ static const struct drm_client_funcs drm_fbdev_client_funcs = {
  *
  * This function sets up fbdev emulation. Restore, hotplug events and
  * teardown are all taken care of. Drivers that do suspend/resume need
- * to call drm_fb_helper_set_suspend_unlocked() themselves. Simple
- * drivers might use drm_mode_config_helper_suspend().
+ * to call drm_client_dev_suspend() and drm_client_dev_resume() by
+ * themselves. Simple drivers might use drm_mode_config_helper_suspend().
  *
  * This function is safe to call even when there are no connectors present.
  * Setup will be retried on the next hotplug event.

drivers/gpu/drm/drm_modeset_helper.c

@@ -21,7 +21,7 @@
  */
 
 #include <drm/drm_atomic_helper.h>
-#include <drm/drm_fb_helper.h>
+#include <drm/drm_client_event.h>
 #include <drm/drm_fourcc.h>
 #include <drm/drm_framebuffer.h>
 #include <drm/drm_modeset_helper.h>
@@ -185,7 +185,7 @@ EXPORT_SYMBOL(drm_crtc_init);
  * Zero on success, negative error code on error.
  *
  * See also:
- * drm_kms_helper_poll_disable() and drm_fb_helper_set_suspend_unlocked().
+ * drm_kms_helper_poll_disable() and drm_client_dev_suspend().
  */
 int drm_mode_config_helper_suspend(struct drm_device *dev)
 {
@@ -199,10 +199,11 @@ int drm_mode_config_helper_suspend(struct drm_device *dev)
 	if (dev->mode_config.poll_enabled)
 		drm_kms_helper_poll_disable(dev);
 
-	drm_fb_helper_set_suspend_unlocked(dev->fb_helper, 1);
+	drm_client_dev_suspend(dev, false);
 	state = drm_atomic_helper_suspend(dev);
 	if (IS_ERR(state)) {
-		drm_fb_helper_set_suspend_unlocked(dev->fb_helper, 0);
+		drm_client_dev_resume(dev, false);
+
 		/*
 		 * Don't enable polling if it was never initialized
 		 */
@@ -230,7 +231,7 @@ EXPORT_SYMBOL(drm_mode_config_helper_suspend);
  * Zero on success, negative error code on error.
  *
  * See also:
- * drm_fb_helper_set_suspend_unlocked() and drm_kms_helper_poll_enable().
+ * drm_client_dev_resume() and drm_kms_helper_poll_enable().
  */
 int drm_mode_config_helper_resume(struct drm_device *dev)
 {
@@ -247,7 +248,8 @@ int drm_mode_config_helper_resume(struct drm_device *dev)
 		DRM_ERROR("Failed to resume (%d)\n", ret);
 	dev->mode_config.suspend_state = NULL;
 
-	drm_fb_helper_set_suspend_unlocked(dev->fb_helper, 0);
+	drm_client_dev_resume(dev, false);
+
 	/*
 	 * Don't enable polling if it is not initialized
 	 */

include/drm/drm_client.h

@@ -63,6 +63,34 @@ struct drm_client_funcs {
 	 * This callback is optional.
 	 */
 	int (*hotplug)(struct drm_client_dev *client);
+
+	/**
+	 * @suspend:
+	 *
+	 * Called when suspending the device.
+	 *
+	 * This callback is optional.
+	 *
+	 * FIXME: Some callers hold the console lock when invoking this
+	 *        function. This interferes with fbdev emulation, which
+	 *        also tries to acquire the lock. Push the console lock
+	 *        into the callback and remove 'holds_console_lock'.
+	 */
+	int (*suspend)(struct drm_client_dev *client, bool holds_console_lock);
+
+	/**
+	 * @resume:
+	 *
+	 * Called when resuming the device from suspend.
+	 *
+	 * This callback is optional.
+	 *
+	 * FIXME: Some callers hold the console lock when invoking this
+	 *        function. This interferes with fbdev emulation, which
+	 *        also tries to acquire the lock. Push the console lock
+	 *        into the callback and remove 'holds_console_lock'.
+	 */
+	int (*resume)(struct drm_client_dev *client, bool holds_console_lock);
 };
 
 /**
@@ -107,6 +135,13 @@ struct drm_client_dev {
 	 */
 	struct drm_mode_set *modesets;
 
+	/**
+	 * @suspended:
+	 *
+	 * The client has been suspended.
+	 */
+	bool suspended;
+
 	/**
 	 * @hotplug_failed:
 	 *

include/drm/drm_client_event.h

@@ -8,5 +8,7 @@ struct drm_device;
 void drm_client_dev_unregister(struct drm_device *dev);
 void drm_client_dev_hotplug(struct drm_device *dev);
 void drm_client_dev_restore(struct drm_device *dev);
+void drm_client_dev_suspend(struct drm_device *dev, bool holds_console_lock);
+void drm_client_dev_resume(struct drm_device *dev, bool holds_console_lock);
 
 #endif