[PATCH v7 5/7] drm/i915/scaler: Limit pipe scaler downscaling factors for YUV420

[Mitul Golani <mitulkumar.ajitkumar.golani@intel.com>]

Limit downscaling to less than 1.5 (source/destination) in
the horizontal direction and 1.0 in the vertical direction,
When configured for Pipe YUV 420 encoding for port output.

Bspec: 50441, 7490, 69901
Signed-off-by: Mitul Golani <mitulkumar.ajitkumar.golani@intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
---
 drivers/gpu/drm/i915/display/skl_scaler.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/skl_scaler.c b/drivers/gpu/drm/i915/display/skl_scaler.c
index 72344044d9d3..c9d7966b37ff 100644
--- a/drivers/gpu/drm/i915/display/skl_scaler.c
+++ b/drivers/gpu/drm/i915/display/skl_scaler.c
@@ -456,6 +456,16 @@ static int intel_atomic_setup_scaler(struct intel_crtc_state *crtc_state,
 		calculate_max_scale(crtc, 0, *scaler_id,
 				    &max_hscale, &max_vscale);
 
+		/*
+		 * When configured for Pipe YUV 420 encoding for port output,
+		 * limit downscaling to less than 1.5 (source/destination) in
+		 * the horizontal direction and 1.0 in the vertical direction.
+		 */
+		if (crtc_state->output_format == INTEL_OUTPUT_FORMAT_YCBCR420) {
+			max_hscale = 0x18000 - 1;
+			max_vscale = 0x10000;
+		}
+
 		hscale = drm_rect_calc_hscale(&src, &crtc_state->pch_pfit.dst,
 					      0, max_hscale);
 		vscale = drm_rect_calc_vscale(&src, &crtc_state->pch_pfit.dst,
-- 
2.48.1