I got the same problem today with sti drm/kms driver and dumb Bo.
The issue comes become hwcomposer because is the master and authenticated on /dev/dri/cardX
Dumb allocation is done by gralloc which does a new open (so it is not authenticated) on drm node the consequence is that we can't use prime functions...
Dumb allocation is done by gralloc which does a new open (so it is not authenticated) on drm node the consequence is that we can't use prime functions...
If you use render node you won't be able to call dumb functions.
To get out of this I think I will implement additional helpers in gem_cma to have ioctl like DRM_GEM_CMA_CREATE and DRM_GEM_CMA_MMAP
and call them instead of dumb so be able to use render node.
Of course it is only for drivers which already use gem_cma helpers (like sti)
Benjamin
Le vendredi 4 décembre 2015, Martin Peres <martin.peres@xxxxxxxxxxxxxxx> a écrit :
On 04/12/15 19:49, Rob Herring wrote:
I'm working on getting Android working with DRM drivers. ATM, I'm
using virtio-gpu as the driver and trying to get just KMS side working
without rendering. I have it working with stock AOSP and the emulated
fb with a few additions to the virtio-gpu driver[1]. Now I'm trying to
get things working with native KMS using drm_gralloc and
drm_hwcomposer (now in AOSP). I've hit one problem though which I'm
not sure how to solve without hacking around it.
Is prime allowed on dumb BOs? AIUI, dumb buffer allocation is not
allowed on render nodes and drmPrimeHandleToFD is not allowed on
card0, so I'm stuck. I could open both nodes, but then I want the case
of no render node to work. After some searching, I thought it was a
matter of needing to do drmAuthMagic, but then found that is
considered obsolete[2].
Obsolete when using render nodes, but still necessary on usual nodes (/dev/dri/cardX) as far as I remember. The usual nodes can do everything the render nodes can do.
Authentication should help! Please make sure you are master or authenticated before doing anything on the usual nodes.
Rob
[1] git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git android-4.4
[2] http://www.x.org/wiki/Events/XDC2013/XDC2013DavidHerrmannDRMSecurity/slides.pdf
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Benjamin Gaignard
Graphic Working Group
Linaro.org │ Open source software for ARM SoCs
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