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

Hi

Am 29.06.20 um 10:40 schrieb Daniel Vetter:

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.

There's userspace that allocates framebuffers in tiles of 64x64 pixels. I think I've seen this with Gnome. So if you have a 800x600 display mode, the allocated framebuffer has a scanline pitch of 832 pixels and the final 32 pixels are ignored.

In regular drivers, we can handle this with the VGA offset register [1] or some equivalent. That's obviously not an option with simplekms, so the different pitch is required.

Best regards Thomas

[1] https://web.stanford.edu/class/cs140/projects/pintos/specs/freevga/vga/crtcr...

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