[PATCH 01/12] drm/i915/skl_watermark: Fix the scaling factor for chroma subsampling

[Ankit Nautiyal <ankit.k.nautiyal@intel.com>]

The Bspec:70151, mentions Chroma subsampling is a 2x downscale
operation. This means that the downscale factor is 2 in each direction.
So correct the downscaling factor to 4.

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Mitul Golani <mitulkumar.ajitkumar.golani@intel.com>
---
 drivers/gpu/drm/i915/display/skl_watermark.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/skl_watermark.c b/drivers/gpu/drm/i915/display/skl_watermark.c
index 33885d619a97..a803e028e1ba 100644
--- a/drivers/gpu/drm/i915/display/skl_watermark.c
+++ b/drivers/gpu/drm/i915/display/skl_watermark.c
@@ -2185,7 +2185,7 @@ dsc_prefill_latency(const struct intel_crtc_state *crtc_state)
 				    crtc_state->hw.adjusted_mode.clock);
 	int num_scaler_users = hweight32(scaler_state->scaler_users);
 	int chroma_downscaling_factor =
-		crtc_state->output_format == INTEL_OUTPUT_FORMAT_YCBCR420 ? 2 : 1;
+		crtc_state->output_format == INTEL_OUTPUT_FORMAT_YCBCR420 ? 4 : 1;
 	u32 dsc_prefill_latency = 0;
 
 	if (!crtc_state->dsc.compression_enable ||
@@ -2228,7 +2228,7 @@ scaler_prefill_latency(const struct intel_crtc_state *crtc_state)
 		u64 hscale_k = max(1000, mul_u32_u32(scaler_state->scalers[0].hscale, 1000) >> 16);
 		u64 vscale_k = max(1000, mul_u32_u32(scaler_state->scalers[0].vscale, 1000) >> 16);
 		int chroma_downscaling_factor =
-			crtc_state->output_format == INTEL_OUTPUT_FORMAT_YCBCR420 ? 2 : 1;
+			crtc_state->output_format == INTEL_OUTPUT_FORMAT_YCBCR420 ? 4 : 1;
 		int latency;
 
 		latency = DIV_ROUND_UP_ULL((4 * linetime * hscale_k * vscale_k *
-- 
2.45.2