On 08/24/2016 06:29 PM, Randy Li wrote:
On 08/18/2016 10:31 AM, Xiang, Haihao wrote:
Hi Randy,
You can get lots of information / docs via internet. You may search for
dri, libdrm, drm, gem, i915 etc.
dri wiki
https://dri.freedesktop.org/wiki/
drm:
https://en.wikipedia.org/wiki/Direct_Rendering_Manager
libdrm:
https://01.org/linuxgraphics/community/libdrm
intel graphics kernel
https://01.org/linuxgraphics/community/kernel
I have read the documents you offered to me, I have a basic view of them
and the relationship of them.
But I want to know more about the detail of Intel implementation.I have
read the Intel driver of VA-API before, I think the Intel video process
video in this way.
1. Allocate the DRI buffer from the kernel driver using the libdrm.
2. Intel DRM driver in kernel would allocate buffer throught the GEM.
3. Intel VA-API driver push the codec data and parameters to those buffers
4. Got result from DRI buffer.
Is it correct ?
[Yakui]: This is right. It works like what you mentioned.
If it is correct, does it mean that the registers(used for configure
decoding parameters) at Intel video processing unit would be mapped as
PRIME buffers to be used in DRI?
And where is the kernel driver do that ? I know it is easy to find the
DRM driver in linux kernel in drivers/gpu/drm/i915/ , but which file is
doing the job for video processing part? They looks like the graphics
to me. I think different Intel platform generation would have a
different registers.
[Yakui]: For the driver's responsibility, it includes the following main
functions.
The first is to allocate the corresponding buffers(For example:
the data buffer, parameter buffer and so on). The buffer allocation is
implemented by using libdrm API. The buffer can be allocated by driver.
And it is also ok to be mapped from the prime buffer, which is allocated
by other component.
The second is to prepare and submit the GPU command buffer. The
GPU command buffer will include all the GPU commands that should be
executed. This will be specific to the platform. BTW: The register
access is also treated as the GPU command. After the GPU command buffer
is submitted, we can then get the expected result.
Thanks
Yakui
Hope it can help you.
Thanks
Haihao
Hi all
I am using VA-API to support the Video Process Unit in a ARM
platform, but it didn't use the standard kernel interface. Without
the
help of DRI, I can't implement something like vaDeriveImage() leading
a lose in performance.
I read the Intel driver, it looks the Intel driver could access
the
the Memory of Video Unit of Intel Graphics card through the libdrm.
If that is right, could somebody told me how does it implemented in
linux kernel(which files?).
And I am really newbies to this area(DRI), could somebody give me
guide and documents about this?
Thank you all very much.
Thank you so much.
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