[RFC 1/3] drm/driver: Add defaults for .gem_prime_export/import callbacks

[Daniel Vetter]

On Fri, Sep 21, 2018 at 06:42:28PM +0200, Noralf Trønnes wrote:
> The majority of drivers use drm_gem_prime_export() and
> drm_gem_prime_import() for these callbacks so let's make them the
> default.
> 
> Signed-off-by: Noralf Trønnes <noralf at tronnes.org>
> ---
>  Documentation/gpu/todo.rst  |  7 +++++++
>  drivers/gpu/drm/drm_prime.c | 10 ++++++++--
>  include/drm/drm_drv.h       |  4 ++++
>  3 files changed, 19 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst
> index 77c2b3c25565..39748e22dea8 100644
> --- a/Documentation/gpu/todo.rst
> +++ b/Documentation/gpu/todo.rst
> @@ -234,6 +234,13 @@ efficient.
>  
>  Contact: Daniel Vetter
>  
> +Defaults for .gem_prime_import and export
> +-----------------------------------------
> +
> +Most drivers don't need to set drm_driver->gem_prime_import and
> +->gem_prime_export now that drm_gem_prime_import() and drm_gem_prime_export()
> +are the default.
> +
>  Core refactorings
>  =================
>  
> diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
> index 3f0205fc0a1a..6721571749ff 100644
> --- a/drivers/gpu/drm/drm_prime.c
> +++ b/drivers/gpu/drm/drm_prime.c
> @@ -559,7 +559,10 @@ static struct dma_buf *export_and_register_object(struct drm_device *dev,
>  		return dmabuf;
>  	}
>  
> -	dmabuf = dev->driver->gem_prime_export(dev, obj, flags);
> +	if (dev->driver->gem_prime_export)
> +		dmabuf = dev->driver->gem_prime_export(dev, obj, flags);
> +	else
> +		dmabuf = drm_gem_prime_export(dev, obj, flags);

Hm, this one here operates on a drm_gem_object (the dev parameter is kinda
redundant). I think this would look neat in the callback structure you're
adding in the next patch. There's also a bunch of gem drivers overwriting
this one, so would make your callbacks structure more generally useful.

Otherwise lgtm.
-Daniel

>  	if (IS_ERR(dmabuf)) {
>  		/* normally the created dma-buf takes ownership of the ref,
>  		 * but if that fails then drop the ref
> @@ -792,7 +795,10 @@ int drm_gem_prime_fd_to_handle(struct drm_device *dev,
>  
>  	/* never seen this one, need to import */
>  	mutex_lock(&dev->object_name_lock);
> -	obj = dev->driver->gem_prime_import(dev, dma_buf);
> +	if (dev->driver->gem_prime_import)
> +		obj = dev->driver->gem_prime_import(dev, dma_buf);
> +	else
> +		obj = drm_gem_prime_import(dev, dma_buf);
>  	if (IS_ERR(obj)) {
>  		ret = PTR_ERR(obj);
>  		goto out_unlock;
> diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
> index 8830e3de3a86..1162145f7f68 100644
> --- a/include/drm/drm_drv.h
> +++ b/include/drm/drm_drv.h
> @@ -471,6 +471,8 @@ struct drm_driver {
>  	 * @gem_prime_export:
>  	 *
>  	 * export GEM -> dmabuf
> +	 *
> +	 * This defaults to drm_gem_prime_export() if not set.
>  	 */
>  	struct dma_buf * (*gem_prime_export)(struct drm_device *dev,
>  				struct drm_gem_object *obj, int flags);
> @@ -478,6 +480,8 @@ struct drm_driver {
>  	 * @gem_prime_import:
>  	 *
>  	 * import dmabuf -> GEM
> +	 *
> +	 * This defaults to drm_gem_prime_import() if not set.
>  	 */
>  	struct drm_gem_object * (*gem_prime_import)(struct drm_device *dev,
>  				struct dma_buf *dma_buf);
> -- 
> 2.15.1
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch