Re: [PATCH 1/9] drm/format-helper: Pass destination pitch to drm_fb_memcpy_dstclip()

[Daniel Vetter <daniel@ffwll.ch>]

On Thu, Jun 25, 2020 at 02:00:03PM +0200, Thomas Zimmermann wrote:
> The memcpy's destination buffer might have a different pitch than the
> source. Support different pitches as function argument.
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>

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

But I do have questions ... why did we allocate a source drm_framebuffer
with mismatching pitch? That sounds backwards, especially for simplekms.

Would be good to add the reasons why we need this to the commit message,
I'm sure I'll discover it later on eventually.
-Daniel

> ---
>  drivers/gpu/drm/drm_format_helper.c    | 9 +++++----
>  drivers/gpu/drm/mgag200/mgag200_mode.c | 2 +-
>  drivers/gpu/drm/tiny/cirrus.c          | 2 +-
>  include/drm/drm_format_helper.h        | 2 +-
>  4 files changed, 8 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
> index c043ca364c86..8d5a683afea7 100644
> --- a/drivers/gpu/drm/drm_format_helper.c
> +++ b/drivers/gpu/drm/drm_format_helper.c
> @@ -52,6 +52,7 @@ EXPORT_SYMBOL(drm_fb_memcpy);
>  /**
>   * drm_fb_memcpy_dstclip - Copy clip buffer
>   * @dst: Destination buffer (iomem)
> + * @dst_pitch: Number of bytes between two consecutive scanlines within dst
>   * @vaddr: Source buffer
>   * @fb: DRM framebuffer
>   * @clip: Clip rectangle area to copy
> @@ -59,12 +60,12 @@ EXPORT_SYMBOL(drm_fb_memcpy);
>   * This function applies clipping on dst, i.e. the destination is a
>   * full (iomem) framebuffer but only the clip rect content is copied over.
>   */
> -void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
> -			   struct drm_framebuffer *fb,
> +void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch,
> +			   void *vaddr, struct drm_framebuffer *fb,
>  			   struct drm_rect *clip)
>  {
>  	unsigned int cpp = fb->format->cpp[0];
> -	unsigned int offset = clip_offset(clip, fb->pitches[0], cpp);
> +	unsigned int offset = clip_offset(clip, dst_pitch, cpp);
>  	size_t len = (clip->x2 - clip->x1) * cpp;
>  	unsigned int y, lines = clip->y2 - clip->y1;
>  
> @@ -73,7 +74,7 @@ void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
>  	for (y = 0; y < lines; y++) {
>  		memcpy_toio(dst, vaddr, len);
>  		vaddr += fb->pitches[0];
> -		dst += fb->pitches[0];
> +		dst += dst_pitch;
>  	}
>  }
>  EXPORT_SYMBOL(drm_fb_memcpy_dstclip);
> diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
> index f16bd278ab7e..7d4f3a62d885 100644
> --- a/drivers/gpu/drm/mgag200/mgag200_mode.c
> +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
> @@ -1586,7 +1586,7 @@ mgag200_handle_damage(struct mga_device *mdev, struct drm_framebuffer *fb,
>  	if (drm_WARN_ON(dev, !vmap))
>  		return; /* BUG: SHMEM BO should always be vmapped */
>  
> -	drm_fb_memcpy_dstclip(mdev->vram, vmap, fb, clip);
> +	drm_fb_memcpy_dstclip(mdev->vram, fb->pitches[0], vmap, fb, clip);
>  
>  	drm_gem_shmem_vunmap(fb->obj[0], vmap);
>  
> diff --git a/drivers/gpu/drm/tiny/cirrus.c b/drivers/gpu/drm/tiny/cirrus.c
> index 744a8e337e41..2dd9e5e31e3d 100644
> --- a/drivers/gpu/drm/tiny/cirrus.c
> +++ b/drivers/gpu/drm/tiny/cirrus.c
> @@ -327,7 +327,7 @@ static int cirrus_fb_blit_rect(struct drm_framebuffer *fb,
>  		goto out_dev_exit;
>  
>  	if (cirrus->cpp == fb->format->cpp[0])
> -		drm_fb_memcpy_dstclip(cirrus->vram,
> +		drm_fb_memcpy_dstclip(cirrus->vram, fb->pitches[0],
>  				      vmap, fb, rect);
>  
>  	else if (fb->format->cpp[0] == 4 && cirrus->cpp == 2)
> diff --git a/include/drm/drm_format_helper.h b/include/drm/drm_format_helper.h
> index 5f9e37032468..2b5036a5fbe7 100644
> --- a/include/drm/drm_format_helper.h
> +++ b/include/drm/drm_format_helper.h
> @@ -11,7 +11,7 @@ struct drm_rect;
>  
>  void drm_fb_memcpy(void *dst, void *vaddr, struct drm_framebuffer *fb,
>  		   struct drm_rect *clip);
> -void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
> +void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch, void *vaddr,
>  			   struct drm_framebuffer *fb,
>  			   struct drm_rect *clip);
>  void drm_fb_swab(void *dst, void *src, struct drm_framebuffer *fb,
> -- 
> 2.27.0
> 

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