Hi Daniel,
El 03/08/18 a las 10:41, Daniel Stone escribió:
Hi Santiago,
On Fri, 3 Aug 2018 at 09:28, Santiago Otero <[email protected]> wrote:
El 03/08/18 a las 09:35, Pekka Paalanen escribió:
No, you cannot use another KMS application at the same time as Weston
is active. The kernel DRM core will forbid access (denies DRM Master
status) if there is already something using KMS, so at any time you can
only run either Weston or some other DRM KMS app.
The fact that you think it is possible suggests that you are using a
deliberately broken downstream kernel. A normal upstream kernel would
deny this.
I think there's no need to get DRM Master if you only want to use another
different plane for drawing (/dev/dri/controlD64). I've got it working this
way.
Control nodes have been removed from upstream kernels a couple of years ago:
https://cgit.freedesktop.org/drm/drm-tip/commit/?id=8a357d10043c75e980e7fcdb60d2b913491564af
From the commit message, it sounds like your downstream kernel tree
has some changes to allow control nodes to be used in this way, since
they did not work out of the box. It will also not work with modern
atomic drivers anymore.
Yes, you're right. I didn't know it. I'm using NXP kernel for iMX8M
(based on version 4.9.88) and it has DRM control nodes back.
My recommendation instead is to rearchitect your software stack so that
Weston will be the only KMS app in the system, and video players push
their content via Wayland through Weston, using e.g. the Wayland dmabuf
extension and Weston's support for overlays (and underlays, if someone
implements them).
I've tried to make it work with Wayland dmabuf with little success. The
performance was bad, there was tearing and it didn't work for HDR video due to
some KMS/DRM properties that I need to set. Using patched Weston and my player
with KMS, now it's working right.
We've had good success with this in the past: the performance has been
completely fine, and tearing is just a result of missing
synchronisation, which at a guess could be improper handling of buffer
release events. GStreamer's waylandsink is a good example of how to
correctly use the interface if that helps.
I've already did some tests with Gstreamer's waylandsink and there was
some tearing in the video. I need to try again.
One problem that I saw was that with Gstreamer's waylandsink there was
some overload due to a lot of calls to drmModeAddFB2 from Weston. I
though that drmModeAddFB2 was only needed first time when you register
the buffer. Doing a strace to Weston process I see a lot of these calls
during Gstreamer playing video with waylandsink:
ioctl(16, DRM_IOCTL_PRIME_FD_TO_HANDLE, 0xffffee93e910) = 0
ioctl(16, DRM_IOCTL_MODE_ADDFB2, 0xffffee93e828) = 0
ioctl(16, DRM_IOCTL_GEM_CLOSE, 0xffffee93e9b0) = 0
I need to do some more tests with my application and linux-dmabuf extension.
Colour management is not yet supported in Weston, but a topic we are working on.
Cheers,
Daniel
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Thank you very much,
Santiago Otero
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