On 1/17/2025 1:11 PM, Mitul Golani wrote:
High refresh rate panels which may have small line times
and vblank sizes, Check if vblank size is sufficient for
enabled scaler users.
--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.
--v4:
- Elaborate commit message and add Bspec number. [Ankit]
- Improvise latency calculation. [Ankit]
- Use ceiling value for down scaling factor when less than 1
as per bspec. [Ankit]
- Correct linetime calculation. [Ankit]
- Consider cdclk prefill adjustment while prefill
computation.[Ankit]
--v5:
- Add Bspec link in commit message trailer. [Ankit]
- Correct hscale, vscale data type.
- Use intel_crtc_compute_min_cdclk. [Ankit]
--v6:
- Update FIXME comment.
- Use cdclk_state->logical.cdclk instead of
intel_crtc_compute_min_cdclk. [Ankit]
Bspec: 70151
Signed-off-by: Mitul Golani <mitulkumar.ajitkumar.golani@xxxxxxxxx>
---
drivers/gpu/drm/i915/display/skl_watermark.c | 50 +++++++++++++++++++-
1 file changed, 49 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/display/skl_watermark.c b/drivers/gpu/drm/i915/display/skl_watermark.c
index f4458d1185b3..c8e540dd66cc 100644
--- a/drivers/gpu/drm/i915/display/skl_watermark.c
+++ b/drivers/gpu/drm/i915/display/skl_watermark.c
@@ -2292,6 +2292,53 @@ static int icl_build_plane_wm(struct intel_crtc_state *crtc_state,
return 0;
}
+static int
+cdclk_prefill_adjustment(const struct intel_crtc_state *crtc_state)
+{
+ struct intel_atomic_state *state =
+ to_intel_atomic_state(crtc_state->uapi.state);
+ const struct intel_cdclk_state *cdclk_state;
+
+ cdclk_state = intel_atomic_get_cdclk_state(state);
+ if (IS_ERR(cdclk_state))
+ return PTR_ERR(cdclk_state);
+
+ return min(1, DIV_ROUND_UP(crtc_state->pixel_rate,
+ 2 * cdclk_state->logical.cdclk));
+}
+
+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 num_scaler_users = hweight32(scaler_state->scaler_users);
+ int latency = 0;
+ int linetime =
+ intel_usecs_to_scanlines(&crtc_state->hw.adjusted_mode,
+ DIV_ROUND_UP(1000 * crtc_state->hw.adjusted_mode.htotal,
+ crtc_state->pixel_rate));
This seems wrong. As per my understanding, linetime in usec should be
htotal * 1000/clock.
+ u64 hscale_k, vscale_k;
+
+ if (!num_scaler_users)
+ return latency;
+
+ latency = intel_usecs_to_scanlines(&crtc_state->hw.adjusted_mode, 4 * linetime);
+
+ if (num_scaler_users > 1) {
+ int chroma_downscaling_factor =
+ crtc_state->output_format == INTEL_OUTPUT_FORMAT_YCBCR420 ? 2 : 1;
+ hscale_k = max(1000, mul_u32_u32(scaler_state->scalers[0].hscale, 1000) >> 16);
+ vscale_k = max(1000, mul_u32_u32(scaler_state->scalers[0].vscale, 1000) >> 16);
+
+ latency += chroma_downscaling_factor *
+ DIV_ROUND_UP_ULL((4 * linetime * hscale_k * vscale_k),
+ 1000000);
+ }
+
+ return latency * cdclk_prefill_adjustment(crtc_state);
The function can return ERR. We should check for error before using this.
Regards,
Ankit
+}
+
static bool
skl_is_vblank_too_short(const struct intel_crtc_state *crtc_state,
int wm0_lines, int latency)
@@ -2299,9 +2346,10 @@ skl_is_vblank_too_short(const struct intel_crtc_state *crtc_state,
const struct drm_display_mode *adjusted_mode =
&crtc_state->hw.adjusted_mode;
- /* FIXME missing scaler and DSC pre-fill time */
+ /* FIXME missing 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;
}
