linux-kernel - [PATCH v3 1/2] drm/mediatek: force hsa hbp hfp packets multiple of lanenum to avoid screen shift

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Date:   Mon, 26 Jul 2021 10:11:03 +0800
From:   Jitao Shi <jitao.shi@...iatek.com>
To:     Chun-Kuang Hu <chunkuang.hu@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>,
        <dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>
CC:     <linux-mediatek@...ts.infradead.org>,
        <linux-arm-kernel@...ts.infradead.org>, <ck.hu@...iatek.com>,
        <stonea168@....com>, <huijuan.xie@...iatek.com>,
        <rex-bc.chen@...iatek.com>, <shuijing.li@...iatek.com>,
        <robh+dt@...nel.org>, <devicetree@...r.kernel.org>,
        Jitao Shi <jitao.shi@...iatek.com>
Subject: [PATCH v3 1/2] drm/mediatek: force hsa hbp hfp packets multiple of lanenum to avoid screen shift

The bridge chip ANX7625 requires the packets on lanes aligned at the end,
or ANX7625 will shift the screen.

Signed-off-by: Jitao Shi <jitao.shi@...iatek.com>
---
 drivers/gpu/drm/mediatek/mtk_dsi.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
index ae403c67cbd9..4735e0092ffe 100644
--- a/drivers/gpu/drm/mediatek/mtk_dsi.c
+++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
@@ -194,6 +194,8 @@ struct mtk_dsi {
 	struct clk *hs_clk;
 
 	u32 data_rate;
+	/* force dsi line end without dsi_null data */
+	bool force_dsi_end_without_null;
 
 	unsigned long mode_flags;
 	enum mipi_dsi_pixel_format format;
@@ -499,6 +501,13 @@ static void mtk_dsi_config_vdo_timing(struct mtk_dsi *dsi)
 		DRM_WARN("HFP + HBP less than d-phy, FPS will under 60Hz\n");
 	}
 
+	if (dsi->force_dsi_end_without_null) {
+		horizontal_sync_active_byte = roundup(horizontal_sync_active_byte, dsi->lanes) - 2;
+		horizontal_frontporch_byte = roundup(horizontal_frontporch_byte, dsi->lanes) - 2;
+		horizontal_backporch_byte = roundup(horizontal_backporch_byte, dsi->lanes) - 2;
+		horizontal_backporch_byte -= (vm->hactive * dsi_tmp_buf_bpp + 2) % dsi->lanes;
+	}
+
 	writel(horizontal_sync_active_byte, dsi->regs + DSI_HSA_WC);
 	writel(horizontal_backporch_byte, dsi->regs + DSI_HBP_WC);
 	writel(horizontal_frontporch_byte, dsi->regs + DSI_HFP_WC);
@@ -1095,6 +1104,10 @@ static int mtk_dsi_probe(struct platform_device *pdev)
 	dsi->bridge.of_node = dev->of_node;
 	dsi->bridge.type = DRM_MODE_CONNECTOR_DSI;
 
+	if (dsi->next_bridge)
+		dsi->force_dsi_end_without_null = of_property_read_bool(dsi->next_bridge->of_node,
+									"force_dsi_end_without_null");
+
 	drm_bridge_add(&dsi->bridge);
 
 	ret = component_add(&pdev->dev, &mtk_dsi_component_ops);
-- 
2.25.1