drm/i915/dsc: Add prefill helper for DSC

Add intel_vdsc_prefill_lines() which tells us how many extra lines
of latency the DSC adds to the pipe prefill.

We shouldn't need a "worst case" vs, "current case" split here
as the DSC state should only change during full modesets.

The returned numbers are in .16 binary fixed point.

Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20251014191808.12326-6-ville.syrjala@linux.intel.com

diff --git a/drivers/gpu/drm/i915/display/intel_vdsc.c b/drivers/gpu/drm/i915/display/intel_vdsc.c
index 8e799e225af17054760447599d387f6ed4ef1468..bca747e24a7fa322caa500f37ae3cb55a2d7f7c1 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_vdsc.c
+++ b/drivers/gpu/drm/i915/display/intel_vdsc.c
@@ -1077,3 +1077,11 @@ int intel_vdsc_min_cdclk(const struct intel_crtc_state *crtc_state)
 
        return min_cdclk;
 }
+
+unsigned int intel_vdsc_prefill_lines(const struct intel_crtc_state *crtc_state)
+{
+       if (!crtc_state->dsc.compression_enable)
+               return 0;
+
+       return 0x18000; /* 1.5 */
+}

diff --git a/drivers/gpu/drm/i915/display/intel_vdsc.h b/drivers/gpu/drm/i915/display/intel_vdsc.h
index 9e2812f99dd74fcbe1c59c70b192f08f26fdeb06..2139391ff881d94f0a7c13d4308e058e04506a3a 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_vdsc.h
+++ b/drivers/gpu/drm/i915/display/intel_vdsc.h
@@ -32,5 +32,6 @@ void intel_dsc_dp_pps_write(struct intel_encoder *encoder,
 void intel_vdsc_state_dump(struct drm_printer *p, int indent,
                           const struct intel_crtc_state *crtc_state);
 int intel_vdsc_min_cdclk(const struct intel_crtc_state *crtc_state);
+unsigned int intel_vdsc_prefill_lines(const struct intel_crtc_state *crtc_state);
 
 #endif /* __INTEL_VDSC_H__ */