[Mesa-dev] [RFC 7/7] radeon: remove screen ref counting

[Rob Herring]

On Fri, Jun 17, 2016 at 2:49 PM, Emil Velikov <emil.l.velikov at gmail.com> wrote:
> On 17 June 2016 at 20:05, Rob Herring <robh at kernel.org> wrote:
>> On Fri, Jun 17, 2016 at 1:45 PM, Emil Velikov <emil.l.velikov at gmail.com> wrote:
>>> On 17 June 2016 at 18:45, Rob Herring <robh at kernel.org> wrote:
>>>> Now that the pipe-loader is reference counting the screen creation, it
>>>> is unnecessary to do in it the winsys/driver.
>>
>> [...]
>>
>>>> -static unsigned hash_dev(void *key)
>>>> -{
>>>> -#if defined(PIPE_ARCH_X86_64)
>>>> -   return pointer_to_intptr(key) ^ (pointer_to_intptr(key) >> 32);
>>>> -#else
>>>> -   return pointer_to_intptr(key);
>>>> -#endif
>>>> -}
>>>> -
>>> As you can see above the hashing algo is different for AMDGPU. Not
>>> familiar with the story behind any of this, so hopefully the AMD folk
>>> will give you some insights.
>>
>> They are also hashing the fd in libdrm amdgpu_device_initialize(), so
>> I thought this was redundant (unless you have an old libdrm).
>>
>>> FWIW I'm inclined to keep the winsys/radeon and winsys/amdgpu
>>> differences separate, although not sure if that's possible.
>>
>> I had planned to, but the unref() function ptr in struct radeon_winsys
>> is shared.
>>
>>> Note that vmwgfx has almost(?) identical implementation that one could nuke.
>>
>> I missed that one...
>>
> As did I a few times :-)
>
>>> Last but not least the biggest and a bit annoying part. As-is the
>>> series will break GL/VDPAU interiop - the 'thing' that inspired all
>>> this work initially.
>>
>> Yeah, I've read thru the bug on that now and am not really clear on
>> the magic that happens there to make it work. If you load 2 libraries
>> with an identical symbol in both only 1 version of the symbol will
>> ever be used?
>>
> Precisely. Only the first "version" of the symbol will be used
> regardless if we have 1 or 101 libraries that reference/have it. Thus
> is how we expose/share the existing device.

So why not just export pipe_loader_drm_probe_fd and
pipe_loader_create_screen or perhaps just
pipe_loader_drm_create_screen?

Rob