[PATCH] drm/panthor: Add DEV_QUERY_TIMESTAMP_INFO dev query

[Mary Guillemard]

> As it stands, this query has nothing to do with the actual GPU so
> doesn't really belong here.
> 
> It'd be more valuable, and can maybe give better calibration results
> than querying the system timestamp separately in userspace, if you
> reported all of:
>  * the system timer value
>  * the system timer frequency
>  * the GPU timer value
>  * the GPU timer frequency (because it _could_ be different in some systems)
>  * the GPU timer offset

I see, I missed those registers... I will also fix this on my v2 of my Panfrost series.

>From my understanding, the GPU timer frequency doesn't have a register
so I suppose it would be wired to cntfrq_el0 if CONFIG_ARM_ARCH_TIMER is
set, am I correct?

Thanks for the review,

Mary