linux-kernel - [PATCH 4/6] drm/msm/dpu: Fix pixel extension sub-sampling

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Message-Id: <20251017-b4-dpu-fixes-v1-4-40ce5993eeb6@gmail.com>
Date: Fri, 17 Oct 2025 19:58:38 +0000
From: Vladimir Lypak <vladimir.lypak@...il.com>
To: Rob Clark <robin.clark@....qualcomm.com>, 
 Dmitry Baryshkov <lumag@...nel.org>, 
 Abhinav Kumar <abhinav.kumar@...ux.dev>, 
 Jessica Zhang <jessica.zhang@....qualcomm.com>, Sean Paul <sean@...rly.run>, 
 Marijn Suijten <marijn.suijten@...ainline.org>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
 Konrad Dybcio <konrad.dybcio@....qualcomm.com>, 
 Kalyan Thota <quic_kalyant@...cinc.com>, 
 Vinod Polimera <quic_vpolimer@...cinc.com>, 
 Konrad Dybcio <konradybcio@...nel.org>, 
 Barnabás Czémán <barnabas.czeman@...nlining.org>
Cc: linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org, 
 freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 Vladimir Lypak <vladimir.lypak@...il.com>
Subject: [PATCH 4/6] drm/msm/dpu: Fix pixel extension sub-sampling

In _dpu_plane_setup_pixel_ext function instead of dividing just chroma
source resolution once (component 1 and 2), second component is divided
once more because src_w and src_h variable is reused between iterations.
Third component receives wrong source resolution too (from component 2).
To fix this introduce temporary variables for each iteration.

Fixes: dabfdd89eaa9 ("drm/msm/disp/dpu1: add inline rotation support for sc7280")
Signed-off-by: Vladimir Lypak <vladimir.lypak@...il.com>
---
 drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
index 6effe0fa4837284a1f038e4907c4c91d239aeb8b..905524ceeb1f192c093f1be7f571b29eb4b53379 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
@@ -500,13 +500,15 @@ static void _dpu_plane_setup_pixel_ext(struct dpu_hw_scaler3_cfg *scale_cfg,
 	int i;
 
 	for (i = 0; i < DPU_MAX_PLANES; i++) {
+		uint32_t w = src_w, h = src_h;
+
 		if (i == DPU_SSPP_COMP_1_2 || i == DPU_SSPP_COMP_2) {
-			src_w /= chroma_subsmpl_h;
-			src_h /= chroma_subsmpl_v;
+			w /= chroma_subsmpl_h;
+			h /= chroma_subsmpl_v;
 		}
 
-		pixel_ext->num_ext_pxls_top[i] = src_h;
-		pixel_ext->num_ext_pxls_left[i] = src_w;
+		pixel_ext->num_ext_pxls_top[i] = h;
+		pixel_ext->num_ext_pxls_left[i] = w;
 	}
 }
 

-- 
2.51.0