[PATCH v2 5/9] drm/i915/dsc: Add prefill helper for DSC

[Ville Syrjala <ville.syrjala@linux.intel.com>]

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

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>
---
 drivers/gpu/drm/i915/display/intel_vdsc.c | 8 ++++++++
 drivers/gpu/drm/i915/display/intel_vdsc.h | 1 +
 2 files changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_vdsc.c b/drivers/gpu/drm/i915/display/intel_vdsc.c
index 8e799e225af1..bca747e24a7f 100644
--- 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 9e2812f99dd7..2139391ff881 100644
--- 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__ */
-- 
2.49.1