linux-kernel - [PATCH v4 2/5] drm: adjust data width for widen bus case

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Message-Id: <20240524-msm-drm-dsc-dsi-video-upstream-4-v4-2-e61c05b403df@linaro.org>
Date: Fri, 24 May 2024 21:18:22 +0800
From: Jun Nie <jun.nie@...aro.org>
To: Rob Clark <robdclark@...il.com>, 
 Abhinav Kumar <quic_abhinavk@...cinc.com>, 
 Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, Sean Paul <sean@...rly.run>, 
 Marijn Suijten <marijn.suijten@...ainline.org>, 
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, 
 Jessica Zhang <quic_jesszhan@...cinc.com>, Vinod Koul <vkoul@...nel.org>
Cc: linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org, 
 freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 Jun Nie <jun.nie@...aro.org>
Subject: [PATCH v4 2/5] drm: adjust data width for widen bus case

data is valid for only half the active window if widebus
is enabled

Signed-off-by: Jun Nie <jun.nie@...aro.org>
---
 drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
index 2cf1f8c116b5..3d1bc8fa4ca2 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
@@ -167,6 +167,14 @@ static void dpu_hw_intf_setup_timing_engine(struct dpu_hw_intf *intf,
 		intf_cfg2 |= INTF_CFG2_DATABUS_WIDEN;
 
 	data_width = p->width;
+	/*
+	 * If widebus is enabled, data is valid for only half the active window
+	 * since the data rate is doubled in this mode. But for the compression
+	 * mode in DP case, the p->width is already adjusted in
+	 * drm_mode_to_intf_timing_params()
+	 */
+	if (p->wide_bus_en && !dp_intf)
+		data_width = p->width >> 1;
 
 	/* TODO: handle DSC+DP case, we only handle DSC+DSI case so far */
 	if (p->compression_en && !dp_intf)

-- 
2.34.1