On Tue, 17 Dec 2024, Mitul Golani <mitulkumar.ajitkumar.golani@xxxxxxxxx> wrote:
> Check if vblank is too short for scaler prefill latency.
>
> Signed-off-by: Mitul Golani <mitulkumar.ajitkumar.golani@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/skl_watermark.c | 22 ++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/skl_watermark.c b/drivers/gpu/drm/i915/display/skl_watermark.c
> index d3506e8ccd9b..a538e2b82c12 100644
> --- a/drivers/gpu/drm/i915/display/skl_watermark.c
> +++ b/drivers/gpu/drm/i915/display/skl_watermark.c
> @@ -2292,6 +2292,27 @@ static int icl_build_plane_wm(struct intel_crtc_state *crtc_state,
> return 0;
> }
>
> +static int
> +scaler_prefill_time(const struct intel_crtc_state *crtc_state)
> +{
> + const struct intel_crtc_scaler_state *scaler_state =
> + &crtc_state->scaler_state;
> + int scaler_users = scaler_state->scaler_users;
> + int count = 0;
> + int hscale = scaler_state->scalers[0].hscale;
> + int vscale = scaler_state->scalers[0].vscale;
> +
> + while (scaler_users) {
> + count += scaler_users & 1;
> + scaler_users >>= 1;
> + }
See the hweight* family of functions for counting bits.
BR,
Jani.
> +
> + if (count > 1)
> + return (4 * crtc_state->linetime * hscale * vscale);
> + else
> + return (4 * crtc_state->linetime);
> +}
> +
> static bool
> skl_is_vblank_too_short(const struct intel_crtc_state *crtc_state,
> int wm0_lines, int latency)
> @@ -2302,6 +2323,7 @@ skl_is_vblank_too_short(const struct intel_crtc_state *crtc_state,
> /* FIXME missing scaler and DSC pre-fill time */
> return crtc_state->framestart_delay +
> intel_usecs_to_scanlines(adjusted_mode, latency) +
> + scaler_prefill_time(crtc_state) +
> wm0_lines >
> adjusted_mode->crtc_vtotal - adjusted_mode->crtc_vblank_start;
> }
--
Jani Nikula, Intel
