Re: [PATCH 3/3] drm: Update documentation and TODO of gem_prime_mmap hook

From: Daniel Vetter <daniel@ffwll.ch>
To: Thomas Zimmermann <tzimmermann@suse.de>
Cc: daniel@ffwll.ch, airlied@linux.ie,
	maarten.lankhorst@linux.intel.com, mripard@kernel.org,
	inki.dae@samsung.com, jy0922.shim@samsung.com,
	sw0312.kim@samsung.com, kyungmin.park@samsung.com,
	krzysztof.kozlowski@canonical.com,
	oleksandr_andrushchenko@epam.com,
	dri-devel@lists.freedesktop.org,
	linux-arm-kernel@lists.infradead.org,
	linux-samsung-soc@vger.kernel.org,
	xen-devel@lists.xenproject.org
Subject: Re: [PATCH 3/3] drm: Update documentation and TODO of gem_prime_mmap hook
Date: Wed, 10 Nov 2021 11:46:48 +0100	[thread overview]
Message-ID: <YYujGLFf+spiXMil@phenom.ffwll.local> (raw)
In-Reply-To: <20211108102846.309-4-tzimmermann@suse.de>

On Mon, Nov 08, 2021 at 11:28:46AM +0100, Thomas Zimmermann wrote:
> The hook gem_prime_mmap in struct drm_driver is deprecated. Document
> the new requirements.
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

> ---
>  Documentation/gpu/todo.rst | 11 -----------
>  include/drm/drm_drv.h      | 11 +++++++----
>  2 files changed, 7 insertions(+), 15 deletions(-)
> 
> diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst
> index 60d1d7ee0719..6593c4c4006e 100644
> --- a/Documentation/gpu/todo.rst
> +++ b/Documentation/gpu/todo.rst
> @@ -268,17 +268,6 @@ Contact: Daniel Vetter
>  
>  Level: Intermediate
>  
> -Clean up mmap forwarding
> -------------------------
> -
> -A lot of drivers forward gem mmap calls to dma-buf mmap for imported buffers.
> -And also a lot of them forward dma-buf mmap to the gem mmap implementations.
> -There's drm_gem_prime_mmap() for this now, but still needs to be rolled out.
> -
> -Contact: Daniel Vetter
> -
> -Level: Intermediate
> -
>  Generic fbdev defio support
>  ---------------------------
>  
> diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
> index 0cd95953cdf5..a84eb4028e5b 100644
> --- a/include/drm/drm_drv.h
> +++ b/include/drm/drm_drv.h
> @@ -345,11 +345,14 @@ struct drm_driver {
>  	 * mmap hook for GEM drivers, used to implement dma-buf mmap in the
>  	 * PRIME helpers.
>  	 *
> -	 * FIXME: There's way too much duplication going on here, and also moved
> -	 * to &drm_gem_object_funcs.
> +	 * This hook only exists for historical reasons. Drivers must use
> +	 * drm_gem_prime_mmap() to implement it.
> +	 *
> +	 * FIXME: Convert all drivers to implement mmap in struct
> +	 * &drm_gem_object_funcs and inline drm_gem_prime_mmap() into
> +	 * its callers. This hook should be removed afterwards.

I think at least i915 has different semantics between dma-buf mmap and gem
mmap in some cases, so this might be tricky to achieve. But I think
everywhere else this should be solid.
-Daniel

>  	 */
> -	int (*gem_prime_mmap)(struct drm_gem_object *obj,
> -				struct vm_area_struct *vma);
> +	int (*gem_prime_mmap)(struct drm_gem_object *obj, struct vm_area_struct *vma);
>  
>  	/**
>  	 * @dumb_create:
> -- 
> 2.33.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

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