Query regarding DRM mastership sharing between multiple process

[Hardik Panchal]

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.

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.

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.

Is my understanding correct? Can we use this method to simultaneously
render from two applications?

Thank you in advance.

Having Addiction of Self-Dependence

*Hardik Panchal*
SDT - Satatya Devices
Contact No. : 9924472937
Email : hardik23398 at gmail.com
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