On Fri, Mar 05, 2021 at 05:44:04PM +0200, Pekka Paalanen wrote: > On Thu, 4 Mar 2021 09:43:22 +0530 > Hardik Panchal <hardik.panchal@xxxxxxxxxxxxxxxx> wrote: > > > Hello Sir/Madam, > > > > I am trying to render some stuff using DRM with Qt GUI application and > > decoded stream from Intel H/w decoder. > > > > I have two applications one is for GUI content and another one is for > > decoded video streams. While doing this I am facing an issue that only > > singal process acquires DRM mastership while the other one is getting > > error. > > Hi, > > yes, this is deliberate and by design. > > The idea of having two separate processes simultaneously controlling > KMS planes of the same CRTC is fundamentally forbidden. Even if it was > not forbidden, doing so would lead to other technical problems. > > You have to change your architecture so that only one process controls > KMS. It you need other processes, they have to pass buffers or > rendering commands to the process that does control KMS. In other > words, you need a display server. One option is kms leases, where the main compositor with exclusive control over the display can pass a select set of resources to another process. But it's a clear lessor/lessee relationship, and the main compositor can always revoke the lease if needed. -Daniel > > > While wondering how to get the privilege to render stuff I came > > across GET_MAGIC and AUTH_MAGIC. > > Please refer to this text from the MAN page of DRM. > > Those will not help you with breaking the DRM master concept. > > > > All DRM devices provide authentication mechanisms. Only a DRM-Master is > > > allowed to perform mode-setting or modify core state and only one user can > > > be DRM-Master at a time. See drmSetMaster > > > <https://www.commandlinux.com/man-page/man3/drmSetMaster.3.html>(3) for > > > information on how to become DRM-Master and what the limitations are. Other > > > DRM users can be authenticated to the DRM-Master via drmAuthMagic > > > <https://www.commandlinux.com/man-page/man3/drmAuthMagic.3.html>(3) so > > > they can perform buffer allocations and rendering. > > > > > > > As per this the client which is authenticated using magic code should be > > able to allocate buffer and rendering. > > But while doing this I am not able to use drmModeSetPlane() for rendering > > stuff on display from an authenticated client application. It is giving me > > Permission Denied. > > > > As per my understanding if the client is authenticated by using > > GET/AUTH_MAGIC it should be able to set a plane and render stuff on the > > display. > > No. Authentication gives access to buffer allocation and submitting > rendering commands to the GPU. It does not give access to KMS. > > > Sorry, > pq > _______________________________________________ > dri-devel mailing list > dri-devel@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
