Commit c3b790ea authored by Daniel Vetter's avatar Daniel Vetter
Browse files

drm: Manage drm_mode_config_init with drmm_ 



drm_mode_config_cleanup is idempotent, so no harm in calling this
twice. This allows us to gradually switch drivers over by removing
explicit drm_mode_config_cleanup calls.

With this step it's now also possible that (at least for simple
drivers) automatic resource cleanup can be done correctly without a
drm_driver->release hook. Therefore allow this now in
devm_drm_dev_init().

Also with drmm_ explicit drm_driver->release hooks are kinda not the
best option: Drivers can always just register their current release
hook with drmm_add_action, but even better they could split them up to
simplify the unwinding for the driver load failure case. So deprecate
that hook to discourage future users.

v2: Fixup the example in the kerneldoc too.

v3:
- For paranoia, double check that minor->dev == dev in the release
  hook, because I botched the pointer math in the drmm library.
- Call drm_mode_config_cleanup when drmm_add_action fails, we'd be
  missing some mutex_destroy and ida_cleanup otherwise (Laurent)

v4: Add a drmm_add_action_or_reset (like devm_ has) to encapsulate this
pattern (Noralf).

v5: Fix oversight in the new drmm_add_action_or_reset macro (Noralf)

v4: Review from Sam:
- drmm_mode_config_init wrapper (also suggested by Thomas)
- improve commit message, explain better why ->relase is deprecated

v5:
- Make drmm_ the main function, with the old one as compat wrapper
  (Sam)
- Add FIXME comments to drm_mode_config_cleanup/init() that drivers
  shouldn't use these anymore.
- Move drmm_add_action_or_reset helper to an earlier patch.

Reviewed-by: default avatarSam Ravnborg <sam@ravnborg.org>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: "Noralf Trønnes" <noralf@tronnes.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: default avatarNoralf Trønnes <noralf@tronnes.org>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200323144950.3018436-27-daniel.vetter@ffwll.ch
parent d33b58d0

Documentation/gpu/drm-kms.rst

+1 −1
Original line number Diff line number Diff line
@@ -3,7 +3,7 @@ Kernel Mode Setting (KMS) 
=========================



Drivers must initialize the mode setting core by calling

drm_mode_config_init() on the DRM device. The function

drmm_mode_config_init() on the DRM device. The function

initializes the :c:type:`struct drm_device <drm_device>`

mode_config field and never fails. Once done, mode configuration must

be setup by initializing the following fields.

drivers/gpu/drm/drm_drv.c

+7 −16
Original line number Diff line number Diff line
@@ -98,6 +98,8 @@ static void drm_minor_alloc_release(struct drm_device *dev, void *data) 
	struct drm_minor *minor = data;

	unsigned long flags;



	WARN_ON(dev != minor->dev);



	put_device(minor->kdev);



	spin_lock_irqsave(&drm_minor_lock, flags);
@@ -266,8 +268,7 @@ void drm_minor_release(struct drm_minor *minor) 
 *

 * The following example shows a typical structure of a DRM display driver.

 * The example focus on the probe() function and the other functions that is

 * almost always present and serves as a demonstration of devm_drm_dev_init()

 * usage with its accompanying drm_driver->release callback.

 * almost always present and serves as a demonstration of devm_drm_dev_init().

 *

 * .. code-block:: c

 *
@@ -277,16 +278,8 @@ void drm_minor_release(struct drm_minor *minor) 
 *		struct clk *pclk;

 *	};

 *

 *	static void driver_drm_release(struct drm_device *drm)

 *	{

 *		struct driver_device *priv = container_of(...);

 *

 *		drm_mode_config_cleanup(drm);

 *	}

 *

 *	static struct drm_driver driver_drm_driver = {

 *		[...]

 *		.release = driver_drm_release,

 *	};

 *

 *	static int driver_probe(struct platform_device *pdev)
@@ -311,7 +304,9 @@ void drm_minor_release(struct drm_minor *minor) 
 *		}

 *		drmm_add_final_kfree(drm, priv);

 *

 *		drm_mode_config_init(drm);

 *		ret = drmm_mode_config_init(drm);

 *		if (ret)

 *			return ret;

 *

 *		priv->userspace_facing = drmm_kzalloc(..., GFP_KERNEL);

 *		if (!priv->userspace_facing)
@@ -709,8 +704,7 @@ static void devm_drm_dev_init_release(void *data) 
 * @driver: DRM driver

 *

 * Managed drm_dev_init(). The DRM device initialized with this function is

 * automatically put on driver detach using drm_dev_put(). You must supply a

 * &drm_driver.release callback to control the finalization explicitly.

 * automatically put on driver detach using drm_dev_put().

 *

 * RETURNS:

 * 0 on success, or error code on failure.
@@ -721,9 +715,6 @@ int devm_drm_dev_init(struct device *parent, 
{

	int ret;



	if (WARN_ON(!driver->release))

		return -EINVAL;



	ret = drm_dev_init(dev, driver, parent);

	if (ret)

		return ret;

drivers/gpu/drm/drm_mode_config.c

+20 −3
Original line number Diff line number Diff line
@@ -25,6 +25,7 @@ 
#include <drm/drm_drv.h>

#include <drm/drm_encoder.h>

#include <drm/drm_file.h>

#include <drm/drm_managed.h>

#include <drm/drm_mode_config.h>

#include <drm/drm_print.h>

#include <linux/dma-resv.h>
@@ -373,8 +374,14 @@ static int drm_mode_create_standard_properties(struct drm_device *dev) 
	return 0;

}



static void drm_mode_config_init_release(struct drm_device *dev, void *ptr)

{

	drm_mode_config_cleanup(dev);

}



/**

 * drm_mode_config_init - initialize DRM mode_configuration structure

 * drmm_mode_config_init - managed DRM mode_configuration structure

 * 	initialization

 * @dev: DRM device

 *

 * Initialize @dev's mode_config structure, used for tracking the graphics
@@ -384,8 +391,12 @@ static int drm_mode_create_standard_properties(struct drm_device *dev) 
 * problem, since this should happen single threaded at init time. It is the

 * driver's problem to ensure this guarantee.

 *

 * Cleanup is automatically handled through registering drm_mode_config_cleanup

 * with drmm_add_action().

 *

 * Returns: 0 on success, negative error value on failure.

 */

void drm_mode_config_init(struct drm_device *dev)

int drmm_mode_config_init(struct drm_device *dev)

{

	mutex_init(&dev->mode_config.mutex);

	drm_modeset_lock_init(&dev->mode_config.connection_mutex);
@@ -443,8 +454,11 @@ void drm_mode_config_init(struct drm_device *dev) 
		drm_modeset_acquire_fini(&modeset_ctx);

		dma_resv_fini(&resv);

	}



	return drmm_add_action_or_reset(dev, drm_mode_config_init_release,

					NULL);

}

EXPORT_SYMBOL(drm_mode_config_init);

EXPORT_SYMBOL(drmm_mode_config_init);



/**

 * drm_mode_config_cleanup - free up DRM mode_config info
@@ -456,6 +470,9 @@ EXPORT_SYMBOL(drm_mode_config_init); 
 * Note that since this /should/ happen single-threaded at driver/device

 * teardown time, no locking is required. It's the driver's job to ensure that

 * this guarantee actually holds true.

 *

 * FIXME: With the managed drmm_mode_config_init() it is no longer necessary for

 * drivers to explicitly call this function.

 */

void drm_mode_config_cleanup(struct drm_device *dev)

{

include/drm/drm_mode_config.h

+17 −1
Original line number Diff line number Diff line
@@ -929,7 +929,23 @@ struct drm_mode_config { 
	const struct drm_mode_config_helper_funcs *helper_private;

};



void drm_mode_config_init(struct drm_device *dev);

int __must_check drmm_mode_config_init(struct drm_device *dev);



/**

 * drm_mode_config_init - DRM mode_configuration structure initialization

 * @dev: DRM device

 *

 * This is the unmanaged version of drmm_mode_config_init() for drivers which

 * still explicitly call drm_mode_config_cleanup().

 *

 * FIXME: This function is deprecated and drivers should be converted over to

 * drmm_mode_config_init().

 */

static inline int drm_mode_config_init(struct drm_device *dev)

{

	return drmm_mode_config_init(dev);

}



void drm_mode_config_reset(struct drm_device *dev);

void drm_mode_config_cleanup(struct drm_device *dev);

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