Set the flag vblank_disable_immediate = true to turn off vblank irqs
immediately as soon as drm_vblank_put is requested so that there are
no irqs triggered during idle state. This will reduce cpu wakeups
and help in power saving.

To enable vblank_disable_immediate flag the underlying KMS driver
needs to support high precision vblank timestamping and also a
reliable way of providing vblank counter which is incrementing
at the leading edge of vblank.

This patch also brings in changes to support vblank_disable_immediate
requirement in dpu driver.

Changes in v1:
 - Specify reason to add vblank timestamp support. (Rob).
 - Add changes to provide vblank counter from dpu driver.

Changes in v2:
 - Fix warn stack reported by Rob Clark with v2 patch.

Changes in v3:
 - Move back to HW frame counter (Rob).

Changes in v4:
 - Frame count mismatch was causing a DRM WARN stack spew.
   DPU HW will increment the frame count at the end of
   the sync, where as vblank will be triggered at the
   fetch_start counter which is calculated as v_total - vfp.
   This is to start fetching early for panels with low
   vbp w.r.t hw latency lines.

   Add logic to detect the line count if it falls between
   vactive and v_total then return incremented frame count value.
Signed-off-by: Kalyan Thota <kalyan_t@codeaurora.org>
Link: https://lore.kernel.org/r/1613651746-12783-1-git-send-email-kalyan_t@codeaurora.orgSigned-off-by: Rob Clark <robdclark@chromium.org>