DRM/V4L2 buffer sharing (was: Re: Patches submitted via linux-media ML that are at patchwork.linuxtv.org)
Hi Laurent,
On 08/15/2012 11:09 PM, Laurent Pinchart wrote:
On Wednesday 15 August 2012 18:13:19 Sylwester Nawrocki wrote:
On 08/15/2012 12:06 AM, Laurent Pinchart wrote:
On Tuesday 14 August 2012 18:37:23 Sylwester Nawrocki wrote:
On 08/14/2012 03:04 PM, Mauro Carvalho Chehab wrote:
This one requires more testing:
May,15 2012: [GIT,PULL,FOR,3.5] DMABUF importer feature in V4L2 API http://patchwork.linuxtv.org/patch/11268 Sylwester Nawrocki s.nawrocki@samsung.com
Hmm, this is not valid any more. Tomasz just posted a new patch series that adds DMABUF importer and exporter feature altogether.
[PATCHv8 00/26] Integration of videobuf2 with DMABUF
I guess we need someone else to submit test patches for other H/W than just Samsung SoCs. I'm not sure if we've got enough resources to port this to other hardware. We have been using these features internally for some time already. It's been 2 kernel releases and I can see only Ack tags from Laurent on Tomasz's patch series, hence it seems there is no wide interest in DMABUF support in V4L2 and this patch series is probably going to stay in a fridge for another few kernel releases.
What would be required to push it to v3.7 ?
Mauro requested more test coverage on that, which is understood since this is a fairly important API enhancement and the V4L2 video overlay API replacement.
We need DMABUF support added at some webcam driver and a DRM driver with prime support (or some V4L2 output driver), I guess it would be best to have that in a PC environment. It looks like i915/radeon/nouveau drivers already have prime support.
uvcvideo has recently been moved to videobuf2, using vb2_vmalloc. I can easily test that, except that I have no idea how to export buffers on the i915 side when X is running. Have you looked into that ?
All right. Yes, I'm also not sure yet how to do it. I tried it on a laptop with i915 driver, but in the running system drmModeGetResources() just fails with EPERM. I've CCed dri-devel, so hopefully someone can shed some light on this.
The DRM driver could be an exporter of buffers that would be passed to the webcam driver.
And except the kernel patches we would need a test application, similar to that one: http://git.infradead.org/users/kmpark/public-apps/blob/a7e755629a74a7ac13788 2032a0f7b2480fa1490:/v4l2-drm-example/dmabuf-sharing.c
I haven't been closely following the DMABUF APIs development, I think Tomasz could provide more details on that.
It's likely I'll get around and prepare a test case as outlined above in coming days. Anyway, it would be appreciated if someone else could give this patch series a try.
I've previously tested the patches on Renesas hardware, exporting buffers on the FBDEV side and importing them on the V4L2 side. We thus have test results for two different platforms, albeit all ARM-based.
I guess ARM is where those APIs will be used mostly, still it would be helpful to have easier reproducible test environment.
--
Thanks, Sylwester
Em 17-08-2012 18:01, Sylwester Nawrocki escreveu:
Hi Laurent,
On 08/15/2012 11:09 PM, Laurent Pinchart wrote:
On Wednesday 15 August 2012 18:13:19 Sylwester Nawrocki wrote:
On 08/15/2012 12:06 AM, Laurent Pinchart wrote:
On Tuesday 14 August 2012 18:37:23 Sylwester Nawrocki wrote:
On 08/14/2012 03:04 PM, Mauro Carvalho Chehab wrote:
This one requires more testing:
May,15 2012: [GIT,PULL,FOR,3.5] DMABUF importer feature in V4L2 API http://patchwork.linuxtv.org/patch/11268 Sylwester Nawrocki s.nawrocki@samsung.com
Hmm, this is not valid any more. Tomasz just posted a new patch series that adds DMABUF importer and exporter feature altogether.
[PATCHv8 00/26] Integration of videobuf2 with DMABUF
I guess we need someone else to submit test patches for other H/W than just Samsung SoCs. I'm not sure if we've got enough resources to port this to other hardware. We have been using these features internally for some time already. It's been 2 kernel releases and I can see only Ack tags from Laurent on Tomasz's patch series, hence it seems there is no wide interest in DMABUF support in V4L2 and this patch series is probably going to stay in a fridge for another few kernel releases.
What would be required to push it to v3.7 ?
Mauro requested more test coverage on that, which is understood since this is a fairly important API enhancement and the V4L2 video overlay API replacement.
We need DMABUF support added at some webcam driver and a DRM driver with prime support (or some V4L2 output driver), I guess it would be best to have that in a PC environment. It looks like i915/radeon/nouveau drivers already have prime support.
uvcvideo has recently been moved to videobuf2, using vb2_vmalloc. I can easily test that, except that I have no idea how to export buffers on the i915 side when X is running. Have you looked into that ?
All right. Yes, I'm also not sure yet how to do it. I tried it on a laptop with i915 driver, but in the running system drmModeGetResources() just fails with EPERM. I've CCed dri-devel, so hopefully someone can shed some light on this.
Likely, you need to run with root permission to use it, or to write an Xorg driver.
It is probably easier to get the V4L driver there, that uses the VIDIOC_OVERLAY stuff, and make it work via DMABUF: http://cgit.freedesktop.org/xorg/driver/xf86-video-v4l/
In order to test it, xawtv has already the code needed to talk with the v4l plugin.
What the plugin does is to export the video board as a XV extension, accessible via xawtv. It currently talks with the display card also via XV, but I believe it won't be hard to port it to work with DMABUF.
As the interface between xawtv and the v4l plugin is just Xv, changing the code there from VIDIOC_OVERLAY to DMABUF should be trivial.
Regards, Mauro
Hi Mauro,
On Friday 17 August 2012 19:03:47 Mauro Carvalho Chehab wrote:
Em 17-08-2012 18:01, Sylwester Nawrocki escreveu:
On 08/15/2012 11:09 PM, Laurent Pinchart wrote:
On Wednesday 15 August 2012 18:13:19 Sylwester Nawrocki wrote:
On 08/15/2012 12:06 AM, Laurent Pinchart wrote:
On Tuesday 14 August 2012 18:37:23 Sylwester Nawrocki wrote:
On 08/14/2012 03:04 PM, Mauro Carvalho Chehab wrote: > This one requires more testing: > > May,15 2012: [GIT,PULL,FOR,3.5] DMABUF importer feature in V4L2 API > > http://patchwork.linuxtv.org/patch/11268 Sylwester > Nawrocki > > s.nawrocki@samsung.com
Hmm, this is not valid any more. Tomasz just posted a new patch series that adds DMABUF importer and exporter feature altogether.
[PATCHv8 00/26] Integration of videobuf2 with DMABUF
I guess we need someone else to submit test patches for other H/W than just Samsung SoCs. I'm not sure if we've got enough resources to port this to other hardware. We have been using these features internally for some time already. It's been 2 kernel releases and I can see only Ack tags from Laurent on Tomasz's patch series, hence it seems there is no wide interest in DMABUF support in V4L2 and this patch series is probably going to stay in a fridge for another few kernel releases.
What would be required to push it to v3.7 ?
Mauro requested more test coverage on that, which is understood since this is a fairly important API enhancement and the V4L2 video overlay API replacement.
We need DMABUF support added at some webcam driver and a DRM driver with prime support (or some V4L2 output driver), I guess it would be best to have that in a PC environment. It looks like i915/radeon/nouveau drivers already have prime support.
uvcvideo has recently been moved to videobuf2, using vb2_vmalloc. I can easily test that, except that I have no idea how to export buffers on the i915 side when X is running. Have you looked into that ?
All right. Yes, I'm also not sure yet how to do it. I tried it on a laptop with i915 driver, but in the running system drmModeGetResources() just fails with EPERM. I've CCed dri-devel, so hopefully someone can shed some light on this.
Likely, you need to run with root permission to use it, or to write an Xorg driver.
It is probably easier to get the V4L driver there, that uses the VIDIOC_OVERLAY stuff, and make it work via DMABUF: http://cgit.freedesktop.org/xorg/driver/xf86-video-v4l/
That won't really help for our test cases. I want to capture from a UVC device using DMABUF import directly to the i915 DRM device using DRM export. In order to do so I will need to get hold of GEM objects that I can use to display the data, possibly through the OpenGL API. I'm looking for help on that last point, I can easily handle the UVC capture code myself.
In order to test it, xawtv has already the code needed to talk with the v4l plugin.
What the plugin does is to export the video board as a XV extension, accessible via xawtv. It currently talks with the display card also via XV, but I believe it won't be hard to port it to work with DMABUF.
As the interface between xawtv and the v4l plugin is just Xv, changing the code there from VIDIOC_OVERLAY to DMABUF should be trivial.
dri-devel@lists.freedesktop.org
-
Laurent Pinchart -
Mauro Carvalho Chehab -
Sylwester Nawrocki