Am 20.06.2016 um 17:39 schrieb Rob Herring:
On Mon, Jun 20, 2016 at 9:27 AM, Christian König
<deathsim...@vodafone.de> wrote:
Am 20.06.2016 um 16:13 schrieb Rob Herring:
On Mon, Jun 20, 2016 at 8:31 AM, Nicolai Hähnle <nhaeh...@gmail.com>
wrote:
On 17.06.2016 21:05, Rob Herring wrote:
On Fri, Jun 17, 2016 at 1:45 PM, Emil Velikov <emil.l.veli...@gmail.com>
wrote:
On 17 June 2016 at 18:45, Rob Herring <r...@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).
Correct. The idea is that there may be non-Mesa users of libdrm_amdgpu
(in
particular, the amdgpu-pro stack).
The hashing in libdrm is different as well, though, and apparently on
purpose, see commit c68d58aa14b7f of libdrm. This might mean the series
doesn't work as is. Christian or Marek might know more.
Okay, so the screen needs to be re-used across card and render nodes.
Seems like other drivers could need that behavior as well and I should
use the libdrm version.
Well not necessarily. Reusing the screen between cards and render nodes only
works if the driver can deal with that.
E.g. for amdgpu we ran into the situation that you can create the screen
initially only with a render node and then get a DRI2 authenticated fd later
on.
What we do in libdrm is to remember the DRI2 authenticated fd separately to
make use of it for flink import/exports. I fear that your cleanup would
break that behavior.
Okay, I'll leave the amdgpu hashing code in place. AFAICT, the
pipe-loader hashing should not impact it. It will only mean that
amdgpu_device_initialize is called once per node.
And I fear that exactly this will break it.
See to work correctly the libdrm implementation must be called with both
file-descriptors. When it then return the same device for both you
should use the same screen object in mesa. Without this the Rander
node/DRI2 dance we do in the winsys will break.
The only solution I can see is to have device specific callbacks to do
the hashing for you.
Regards,
Christian.
Rob
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