Re: [RFC] Host1x/TegraDRM UAPI

[Dmitry Osipenko <digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

23.06.2020 15:09, Mikko Perttunen пишет:
> /* Command is an opcode gather from a GEM handle */
> #define DRM_TEGRA_SUBMIT_COMMAND_GATHER             0
> /* Command is an opcode gather from a user pointer */
> #define DRM_TEGRA_SUBMIT_COMMAND_GATHER_UPTR        1

I'm a bit dubious about whether we really need to retain the non-UPTR
variant. The memory-copying overhead is negligible because cmdstream's
data usually is hot in CPU's cache

IIRC, the most (if not all) of the modern DRM drivers drivers use the
usrptr-only for the cmdstream.

At least there is no any real-world userspace example today that could
benefit from a non-UPTR variant.

I'm suggesting to leave out the non-UPTR gather variant for now, keeping
it in mind as a potential future extension of the submission UAPI. Any
objections?