Re: [PATCH v4 5/9] drm/client: Add client callbacks

Noralf Trønnes <noralf@xxxxxxxxxxx> · Tue, 3 Jul 2018 15:07:50 +0200

Den 03.07.2018 09.46, skrev Daniel Vetter:
On Mon, Jul 02, 2018 at 03:54:29PM +0200, Noralf Trønnes wrote:
Add client callbacks and hook them up.
Add a list of clients per drm_device.

Signed-off-by: Noralf Trønnes <noralf@xxxxxxxxxxx>
btw for reviewing it'd be simpler if you merge the 2 patches that add the
client library, avoids me having to jump back&forth ..

Bunch of comments below still.
-Daniel

---
  drivers/gpu/drm/drm_client.c        | 92 ++++++++++++++++++++++++++++++++++++-
  drivers/gpu/drm/drm_drv.c           |  7 +++
  drivers/gpu/drm/drm_fb_cma_helper.c |  2 +-
  drivers/gpu/drm/drm_fb_helper.c     | 11 ++++-
  drivers/gpu/drm/drm_file.c          |  3 ++
  drivers/gpu/drm/drm_probe_helper.c  |  3 ++
  include/drm/drm_client.h            | 75 +++++++++++++++++++++++++++++-
  include/drm/drm_device.h            | 14 ++++++
  8 files changed, 201 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/drm_client.c b/drivers/gpu/drm/drm_client.c
index 9c9b8ac7aea3..f05ee98bd10c 100644
--- a/drivers/gpu/drm/drm_client.c
+++ b/drivers/gpu/drm/drm_client.c
@@ -4,6 +4,7 @@
   */
  
  #include <linux/list.h>
+#include <linux/module.h>
  #include <linux/mutex.h>
  #include <linux/seq_file.h>
  #include <linux/slab.h>
@@ -66,6 +67,7 @@ EXPORT_SYMBOL(drm_client_close);
   * @dev: DRM device
   * @client: DRM client
   * @name: Client name
+ * @funcs: DRM client functions (optional)
   *
   * Use drm_client_put() to free the client.
   *
@@ -73,24 +75,47 @@ EXPORT_SYMBOL(drm_client_close);
   * Zero on success or negative error code on failure.
   */
  int drm_client_new(struct drm_device *dev, struct drm_client_dev *client,
-		   const char *name)
+		   const char *name, const struct drm_client_funcs *funcs)
  {
+	bool registered;
  	int ret;
  
  	if (!drm_core_check_feature(dev, DRIVER_MODESET) ||
  	    !dev->driver->dumb_create || !dev->driver->gem_prime_vmap)
  		return -ENOTSUPP;
  
+	if (funcs && !try_module_get(funcs->owner))
+		return -ENODEV;
+
  	client->dev = dev;
  	client->name = name;
+	client->funcs = funcs;
  
  	ret = drm_client_open(client);
  	if (ret)
-		return ret;
+		goto err_put_module;
+
+	mutex_lock(&dev->clientlist_mutex);
+	registered = dev->registered;
+	if (registered)
+		list_add(&client->list, &dev->clientlist);
+	mutex_unlock(&dev->clientlist_mutex);
+	if (!registered) {
+		ret = -ENODEV;
+		goto err_close;
+	}
  
  	drm_dev_get(dev);
This only works if the caller holds a reference for us on dev already, or
has some other guarantee that it won't disappear. Would be good to mention
this in the kerneldoc.

  	return 0;
+
+err_close:
+	drm_client_close(client);
+err_put_module:
+	if (funcs)
+		module_put(funcs->owner);
+
+	return ret;
  }
  EXPORT_SYMBOL(drm_client_new);
  
@@ -116,9 +141,72 @@ void drm_client_release(struct drm_client_dev *client)
  
  	drm_client_close(client);
  	drm_dev_put(dev);
+	if (client->funcs)
+		module_put(client->funcs->owner);
  }
  EXPORT_SYMBOL(drm_client_release);
  
+void drm_client_dev_unregister(struct drm_device *dev)
+{
+	struct drm_client_dev *client, *tmp;
+
+	if (!drm_core_check_feature(dev, DRIVER_MODESET))
+		return;
+
+	mutex_lock(&dev->clientlist_mutex);
+	list_for_each_entry_safe(client, tmp, &dev->clientlist, list) {
+		list_del(&client->list);
+		if (client->funcs && client->funcs->unregister) {
+			client->funcs->unregister(client);
Hm, not ->unregister is called while holding the lock. I thought that
blows up for you?

It is fine now that we decided that the client can't remove itself.
Only the driver can do it on drm_dev_unregister().

+		} else {
+			drm_client_release(client);
+			kfree(client);
+		}
+	}
+	mutex_unlock(&dev->clientlist_mutex);
+}
+
Needs a bit of kerneldoc here since exported function. Drivers might also
want to call this from their own hotplug handling.

drm_client_dev_hotplug() is only called by drm_kms_helper_hotplug_event().
The reason it's exported is because the helper can be built as a module.

Noralf.

+void drm_client_dev_hotplug(struct drm_device *dev)
+{
+	struct drm_client_dev *client;
+	int ret;
+
+	if (!drm_core_check_feature(dev, DRIVER_MODESET))
+		return;
+
+	mutex_lock(&dev->clientlist_mutex);
+	list_for_each_entry(client, &dev->clientlist, list) {
+		if (!client->funcs || !client->funcs->hotplug)
+			continue;
+
+		ret = client->funcs->hotplug(client);
+		DRM_DEV_DEBUG_KMS(dev->dev, "%s: ret=%d\n", client->name, ret);
+	}
+	mutex_unlock(&dev->clientlist_mutex);
+}
+EXPORT_SYMBOL(drm_client_dev_hotplug);
+
+void drm_client_dev_restore(struct drm_device *dev)
+{
+	struct drm_client_dev *client;
+	int ret;
+
+	if (!drm_core_check_feature(dev, DRIVER_MODESET))
+		return;
+
+	mutex_lock(&dev->clientlist_mutex);
+	list_for_each_entry(client, &dev->clientlist, list) {
+		if (!client->funcs || !client->funcs->restore)
+			continue;
+
+		ret = client->funcs->restore(client);
+		DRM_DEV_DEBUG_KMS(dev->dev, "%s: ret=%d\n", client->name, ret);
+		if (!ret) /* The first one to return zero gets the privilege to restore */
+			break;
+	}
+	mutex_unlock(&dev->clientlist_mutex);
+}
+
  static void drm_client_buffer_delete(struct drm_client_buffer *buffer)
  {
  	struct drm_device *dev = buffer->client->dev;
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index e7ff0b03328b..6eb935bb2f92 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -34,6 +34,7 @@
  #include <linux/slab.h>
  #include <linux/srcu.h>
  
+#include <drm/drm_client.h>
  #include <drm/drm_drv.h>
  #include <drm/drmP.h>
  
@@ -506,6 +507,7 @@ int drm_dev_init(struct drm_device *dev,
  
  	INIT_LIST_HEAD(&dev->filelist);
  	INIT_LIST_HEAD(&dev->filelist_internal);
+	INIT_LIST_HEAD(&dev->clientlist);
  	INIT_LIST_HEAD(&dev->ctxlist);
  	INIT_LIST_HEAD(&dev->vmalist);
  	INIT_LIST_HEAD(&dev->maplist);
@@ -515,6 +517,7 @@ int drm_dev_init(struct drm_device *dev,
  	spin_lock_init(&dev->event_lock);
  	mutex_init(&dev->struct_mutex);
  	mutex_init(&dev->filelist_mutex);
+	mutex_init(&dev->clientlist_mutex);
  	mutex_init(&dev->ctxlist_mutex);
  	mutex_init(&dev->master_mutex);
  
@@ -570,6 +573,7 @@ int drm_dev_init(struct drm_device *dev,
  err_free:
  	mutex_destroy(&dev->master_mutex);
  	mutex_destroy(&dev->ctxlist_mutex);
+	mutex_destroy(&dev->clientlist_mutex);
  	mutex_destroy(&dev->filelist_mutex);
  	mutex_destroy(&dev->struct_mutex);
  	return ret;
@@ -604,6 +608,7 @@ void drm_dev_fini(struct drm_device *dev)
  
  	mutex_destroy(&dev->master_mutex);
  	mutex_destroy(&dev->ctxlist_mutex);
+	mutex_destroy(&dev->clientlist_mutex);
  	mutex_destroy(&dev->filelist_mutex);
  	mutex_destroy(&dev->struct_mutex);
  	kfree(dev->unique);
@@ -859,6 +864,8 @@ void drm_dev_unregister(struct drm_device *dev)
  
  	dev->registered = false;
  
+	drm_client_dev_unregister(dev);
+
  	if (drm_core_check_feature(dev, DRIVER_MODESET))
  		drm_modeset_unregister_all(dev);
  
diff --git a/drivers/gpu/drm/drm_fb_cma_helper.c b/drivers/gpu/drm/drm_fb_cma_helper.c
index 5762a7c441e9..718c7f961d8a 100644
--- a/drivers/gpu/drm/drm_fb_cma_helper.c
+++ b/drivers/gpu/drm/drm_fb_cma_helper.c
@@ -181,7 +181,7 @@ struct drm_fbdev_cma *drm_fbdev_cma_init(struct drm_device *dev,
  
  	fb_helper = &fbdev_cma->fb_helper;
  
-	ret = drm_client_new(dev, &fb_helper->client, "fbdev");
+	ret = drm_client_new(dev, &fb_helper->client, "fbdev", NULL);
  	if (ret)
  		goto err_free;
  
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 0a0a577ebc3c..bea3a0cb324a 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -2989,8 +2989,15 @@ static void drm_fbdev_fb_destroy(struct fb_info *info)
  	}
  
  	drm_client_framebuffer_delete(fb_helper->buffer);
-	drm_client_release(&fb_helper->client);
-	kfree(fb_helper);
+	/*
+	 * FIXME:
+	 * Remove conditional when all CMA drivers have been moved over to using
+	 * drm_fbdev_generic_setup().
+	 */
+	if (fb_helper->client.funcs) {
+		drm_client_release(&fb_helper->client);
+		kfree(fb_helper);
+	}
  }
  
  static int drm_fbdev_fb_mmap(struct fb_info *info, struct vm_area_struct *vma)
diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
index 66bb403dc8ab..ffa8dc35515f 100644
--- a/drivers/gpu/drm/drm_file.c
+++ b/drivers/gpu/drm/drm_file.c
@@ -35,6 +35,7 @@
  #include <linux/slab.h>
  #include <linux/module.h>
  
+#include <drm/drm_client.h>
  #include <drm/drm_file.h>
  #include <drm/drmP.h>
  
@@ -444,6 +445,8 @@ void drm_lastclose(struct drm_device * dev)
  
  	if (drm_core_check_feature(dev, DRIVER_LEGACY))
  		drm_legacy_dev_reinit(dev);
+
+	drm_client_dev_restore(dev);
  }
  
  /**
diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
index 527743394150..26be57e28a9d 100644
--- a/drivers/gpu/drm/drm_probe_helper.c
+++ b/drivers/gpu/drm/drm_probe_helper.c
@@ -33,6 +33,7 @@
  #include <linux/moduleparam.h>
  
  #include <drm/drmP.h>
+#include <drm/drm_client.h>
  #include <drm/drm_crtc.h>
  #include <drm/drm_fourcc.h>
  #include <drm/drm_crtc_helper.h>
@@ -563,6 +564,8 @@ void drm_kms_helper_hotplug_event(struct drm_device *dev)
  	drm_sysfs_hotplug_event(dev);
  	if (dev->mode_config.funcs->output_poll_changed)
  		dev->mode_config.funcs->output_poll_changed(dev);
+
+	drm_client_dev_hotplug(dev);
  }
  EXPORT_SYMBOL(drm_kms_helper_hotplug_event);
  
diff --git a/include/drm/drm_client.h b/include/drm/drm_client.h
index e366f95d4414..02cbb02714d8 100644
--- a/include/drm/drm_client.h
+++ b/include/drm/drm_client.h
@@ -5,10 +5,66 @@
  
  #include <linux/types.h>
  
+struct drm_client_dev;
  struct drm_device;
  struct drm_file;
  struct drm_framebuffer;
  struct drm_gem_object;
+struct module;
+
+/**
+ * struct drm_client_funcs - DRM client callbacks
+ */
+struct drm_client_funcs {
+	/**
+	 * @owner: The module owner
+	 */
+	struct module *owner;
+
+	/**
+	 * @release:
+	 *
+	 * Called when the reference count is dropped to zero. Users of this
+	 * callback is responsible for calling drm_client_close() and freeing
+	 * the client structure.
+	 *
+	 * This callback is optional.
+	 */
+	void (*release)(struct drm_client_dev *client);
Hm, is this no longer in use?

+
+	/**
+	 * @unregister:
+	 *
+	 * Called when &drm_device is unregistered. The client should respond by
+	 * releasing it's resources using drm_client_put(). If it can't do so
+	 * due to resoruces being tied up, like fbdev with open file handles,
+	 * it should release it's resources as soon as possible.
This still talks about refcounting and _put ... needs a refresher.

+	 *
+	 * This callback is optional.
+	 */
+	void (*unregister)(struct drm_client_dev *client);
+
+	/**
+	 * @restore:
+	 *
+	 * Called on drm_lastclose(). The first client instance in the list that
+	 * returns zero gets the privilege to restore and no more clients are
+	 * called. This callback is not called after @unregister has been called.
+	 *
+	 * This callback is optional.
+	 */
+	int (*restore)(struct drm_client_dev *client);
+
+	/**
+	 * @hotplug:
+	 *
+	 * Called on drm_kms_helper_hotplug_event().
+	 * This callback is not called after @unregister has been called.
+	 *
+	 * This callback is optional.
+	 */
+	int (*hotplug)(struct drm_client_dev *client);
+};
  
  /**
   * struct drm_client_dev - DRM client instance
@@ -24,6 +80,19 @@ struct drm_client_dev {
  	 */
  	const char *name;
  
+	/**
+	 * @list:
+	 *
+	 * List of all clients of a DRM device, linked into
+	 * &drm_device.clientlist. Protected by &drm_device.clientlist_mutex.
+	 */
+	struct list_head list;
+
+	/**
+	 * @funcs: DRM client functions (optional)
+	 */
+	const struct drm_client_funcs *funcs;
+
  	/**
  	 * @file: DRM file
  	 */
@@ -31,9 +100,13 @@ struct drm_client_dev {
  };
  
  int drm_client_new(struct drm_device *dev, struct drm_client_dev *client,
-		   const char *name);
+		   const char *name, const struct drm_client_funcs *funcs);
  void drm_client_release(struct drm_client_dev *client);
  
+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);
+
  /**
   * struct drm_client_buffer - DRM client buffer
   */
diff --git a/include/drm/drm_device.h b/include/drm/drm_device.h
index 9e29976d4e98..f9c6e0e3aec7 100644
--- a/include/drm/drm_device.h
+++ b/include/drm/drm_device.h
@@ -81,6 +81,20 @@ struct drm_device {
  	 */
  	struct list_head filelist_internal;
  
+	/**
+	 * @clientlist_mutex:
+	 *
+	 * Protects @clientlist access.
+	 */
+	struct mutex clientlist_mutex;
+
+	/**
+	 * @clientlist:
+	 *
+	 * List of in-kernel clients. Protected by @clientlist_mutex.
+	 */
+	struct list_head clientlist;
+
  	/** \name Memory management */
  	/*@{ */
  	struct list_head maplist;	/**< Linked list of regions */
--
2.15.1

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