Add a new helper thingy to deal with the pipe prefill latency.
We get three potentially useful thigns out of this:
- skl_prefill_vblank_too_short() used for checking the
actual vblank/guardband length
- skl_prefill_min_guardband() to calculate a suitable guardband
size based on some worst case scaling/etc. estimates
- skl_prefill_min_cdclk() used to calculate a minimum cdclk
frequency required for very small vblank lengths (in case the
otherwise computed minimum cdclk doesn't result in fast enough
prefill).
The internal arithmetic is done terms of scanlines using .16
binary fixed point representation.
v2: Add the missing <<16 for framestart_delay
Drop the cdclk_state stuff in favor of crtc_state->min_cdclk
Rename to skl_prefill since this is skl+ only
Use intel_crtc_vblank_length() instead of hand rolling it
memset(0) in prefill_init()
Reviewed-by: Uma Shankar <uma.shankar@intel.com> #v1
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20251014191808.12326-9-ville.syrjala@linux.intel.com
