[PATCH 27/52] drm: Manage drm_mode_config_init with drmm_

[Laurent Pinchart]

Hi Daniel,

Thank you for the patch.

On Wed, Feb 19, 2020 at 11:20:57AM +0100, Daniel Vetter wrote:
> 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 not 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, so deprecate that hook to discourage future users.
> 
> v2: Fixup the example in the kerneldoc too.
> 
> Cc: "Noralf Trønnes" <noralf at tronnes.org>
> Cc: Sam Ravnborg <sam at ravnborg.org>
> Cc: Thomas Zimmermann <tzimmermann at suse.de>
> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> ---
>  drivers/gpu/drm/drm_drv.c         | 21 +++++----------------
>  drivers/gpu/drm/drm_mode_config.c | 12 +++++++++++-
>  include/drm/drm_mode_config.h     |  2 +-
>  3 files changed, 17 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> index 3cf40864d4a6..428c569aaaf1 100644
> --- a/drivers/gpu/drm/drm_drv.c
> +++ b/drivers/gpu/drm/drm_drv.c
> @@ -267,8 +267,7 @@ 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
>   *
> @@ -278,16 +277,8 @@ 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)
> @@ -312,7 +303,9 @@ void drm_minor_release(struct drm_minor *minor)
>   *		}
>   *		drmm_add_final_kfree(drm, priv);
>   *
> - *		drm_mode_config_init(drm);
> + *		ret = drm_mode_config_init(drm);
> + *		if (ret)
> + *			return ret;
>   *
>   *		priv->userspace_facing = drmm_kzalloc(..., GFP_KERNEL);
>   *		if (!priv->userspace_facing)
> @@ -710,8 +703,7 @@ 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.
> @@ -722,9 +714,6 @@ 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;
> diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
> index 08e6eff6a179..957db1edba0c 100644
> --- a/drivers/gpu/drm/drm_mode_config.c
> +++ b/drivers/gpu/drm/drm_mode_config.c
> @@ -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>
> @@ -373,6 +374,11 @@ 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
>   * @dev: DRM device
> @@ -384,8 +390,10 @@ 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().
>   */
> -void drm_mode_config_init(struct drm_device *dev)
> +int drm_mode_config_init(struct drm_device *dev)
>  {
>  	mutex_init(&dev->mode_config.mutex);
>  	drm_modeset_lock_init(&dev->mode_config.connection_mutex);
> @@ -443,6 +451,8 @@ void drm_mode_config_init(struct drm_device *dev)
>  		drm_modeset_acquire_fini(&modeset_ctx);
>  		dma_resv_fini(&resv);
>  	}
> +
> +	return drmm_add_action(dev, drm_mode_config_init_release, NULL);

If this fails, shouldn't drm_mode_config_cleanup() be called here ?

>  }
>  EXPORT_SYMBOL(drm_mode_config_init);
>  
> diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h
> index 3bcbe30339f0..160a3e4b51c3 100644
> --- a/include/drm/drm_mode_config.h
> +++ b/include/drm/drm_mode_config.h
> @@ -929,7 +929,7 @@ struct drm_mode_config {
>  	const struct drm_mode_config_helper_funcs *helper_private;
>  };
>  
> -void drm_mode_config_init(struct drm_device *dev);
> +int drm_mode_config_init(struct drm_device *dev);
>  void drm_mode_config_reset(struct drm_device *dev);
>  void drm_mode_config_cleanup(struct drm_device *dev);
>  

-- 
Regards,

Laurent Pinchart