Check if vblank is too short for scaler prefill latency.
--v2:
- Use hweight* family of functions for counting bits. [Jani]
- Update precision handling for hscale and vscale. [Ankit]
- Consider chroma downscaling factor during latency
calculation. [Ankit]
- Replace function name from scaler_prefill_time to
scaler_prefill_latency.
--v3:
- hscale_k and vscale_k values are already left shifted by 16,
after multiplying by 1000, those need to be right shifted to 16. [Ankit]
- Replace YCBCR444 to YCBCR420. [Ankit]
- Divide by 1000 * 1000 in end to get correct precision. [Ankit]
- Initialise latency to 0 to avoid any garbage.
Signed-off-by: Mitul Golani <mitulkumar.ajitkumar.golani@xxxxxxxxx>
---
drivers/gpu/drm/i915/display/skl_watermark.c | 31 ++++++++++++++++++++
1 file changed, 31 insertions(+)
diff --git a/drivers/gpu/drm/i915/display/skl_watermark.c b/drivers/gpu/drm/i915/display/skl_watermark.c
index f4458d1185b3..fe91854e456c 100644
--- a/drivers/gpu/drm/i915/display/skl_watermark.c
+++ b/drivers/gpu/drm/i915/display/skl_watermark.c
@@ -2292,6 +2292,36 @@ static int icl_build_plane_wm(struct intel_crtc_state *crtc_state,
return 0;
}
+static int
+scaler_prefill_latency(const struct intel_crtc_state *crtc_state)
+{
+ const struct intel_crtc_scaler_state *scaler_state =
+ &crtc_state->scaler_state;
+ int count = hweight32(scaler_state->scaler_users);
+ int latency = 0;
+ long long hscale_k =
+ mul_u32_u32(scaler_state->scalers[0].hscale, 1000) >> 16;
+ long long vscale_k =
+ mul_u32_u32(scaler_state->scalers[0].vscale, 1000) >> 16;
+
+ if (!count)
+ return latency;
+
+ if (count > 1) {
+ int chroma_downscaling_factor =
+ crtc_state->output_format == INTEL_OUTPUT_FORMAT_YCBCR420 ? 2 : 1;
+
+ latency = (4 * crtc_state->linetime) +
+ (chroma_downscaling_factor *
+ DIV_ROUND_UP_ULL((4 * crtc_state->linetime * hscale_k * vscale_k),
+ 1000000));
+ } else {
+ latency = 4 * crtc_state->linetime;
+ }
+
+ return latency;
+}
+
static bool
skl_is_vblank_too_short(const struct intel_crtc_state *crtc_state,
int wm0_lines, int latency)
@@ -2302,6 +2332,7 @@ 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_latency(crtc_state) +
wm0_lines >
adjusted_mode->crtc_vtotal - adjusted_mode->crtc_vblank_start;
}
--
2.46.0
