Re: [PATCH] vmwgfx: use monotonic event timestamps

[Arnd Bergmann]

On Wed, Dec 13, 2017 at 9:56 PM, Sinclair Yeh <syeh@xxxxxxxxxx> wrote:
> This looks okay to me.  Although we should change eaction->tv_* type
> to 64-bit as well.

I thought about it but it would add significant complication without real gain,
as the  eaction->tv_* pointers point into uapi structures (drm_vmw_event_fence
and drm_event_vblank) that are defined as 32-bit times and cannot be
changed. Changing the temporary pointer to 64 bit would require adding
a temporary variable to point to and then doing the truncation in the
callers. With monotonic times, we know that 32-bit times are sufficient,
they are good for 136 years after boot (68 years when interpreted as
signed).

       Arnd