[PATCH 02/23] drm/amdgpu: change wptr to 64 bits

[Jerome Glisse]

On Thu, Mar 09, 2017 at 10:57:27AM +0100, Christian König wrote:
> Am 09.03.2017 um 04:44 schrieb Alex Deucher:
> > From: Ken Wang <Qingqing.Wang at amd.com>
> > 
> > Newer asics use 64 bit wptrs
> 
> We need a better patch description. Newer asics doesn't use 64bit wptrs, but
> rather need them!
> 
> E.g. if the wptr is now smaller than the rptr that doesn't indicate a wrap
> around any more.

What does it means ? Doesn't make sense, you are allocating 1TB command
buffer and know you will never run out of space ? ;)

Either we are talking about a ring buffer and then wptr < rptr means wrap
around or we are talking about something new that is not a ring buffer.

64 bits or 32 bits doesn't matter from ring buffer point of view. So i
am puzzle about what this new thing is. Anywhere i can read about this
new command buffer thingy ? Because from where i stand it looks like it
would be better to be something else than a ring buffer if there is no
wrap around.

Cheers,
Jérôme