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

[Gerd Hoffmann]

  Hi,

> > I don't quite remember where exactly this was implemented. It was not a
> > shared buffer, though. IIRC the buffer allocation code in one of the
> > libs rounded the size towards multiples of 64. I remember thinking that
> > it was probably done for tiled rendering.

Happens when running gnome in wayland mode, so whatever the display
server is in that case (mutter?) or one of the libraries it uses.

> Yeah, but you don't do rendering on dumb buffers. Like ever. So this
> smells like a userspace bug.
> 
> If it's for shared buffers then I think that sounds more reasonable.

Well, wayland can use dma-bufs for buffer sharing between wayland server
and wayland client.  Dunno whenever it also does that for the software
rendering case, and I have absolutely no idea how the buffer allocation
code paths look like.  But possibly it isn't known at buffer allocation
time whenever a given buffer will be touched by a gpu at some point in
the future?

take care,
  Gerd