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From: Icenowy Zheng <icenowy@aosc.io>
To: Maxime Ripard <mripard@kernel.org>, Chen-Yu Tsai <wens@csie.org>,
	David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>
Cc: linux-sunxi@googlegroups.com, Icenowy Zheng <icenowy@aosc.io>,
	linux-arm-kernel@lists.infradead.org,
	dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Subject: [PATCH 2/3] drm/sun4i: dsi: fix DRQ calculation
Date: Tue,  1 Oct 2019 16:02:52 +0800	[thread overview]
Message-ID: <20191001080253.6135-3-icenowy@aosc.io> (raw)
In-Reply-To: <20191001080253.6135-1-icenowy@aosc.io>

According to the BSP source code, when calculating the magic DRQ value
outside burst mode, a formula of "lcd_ht - lcd_x - lcd_hbp", which is
interpreted as right margin (HFP value). However, currently the
sun6i_mipi_dsi driver code calculates it wrongly as HFP + sync length,
which lead to timing error.

Fix the DRQ calculation by change it to use HFP.

Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
---
 drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
index c86e11631ebc..2d3e822a7739 100644
--- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
+++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
@@ -436,9 +436,9 @@ static void sun6i_dsi_setup_burst(struct sun6i_dsi *dsi,
 			     SUN6I_DSI_BURST_LINE_SYNC_POINT(SUN6I_DSI_SYNC_POINT));
 
 		val = SUN6I_DSI_TCON_DRQ_ENABLE_MODE;
-	} else if ((mode->hsync_end - mode->hdisplay) > 20) {
+	} else if ((mode->hsync_start - mode->hdisplay) > 20) {
 		/* Maaaaaagic */
-		u16 drq = (mode->hsync_end - mode->hdisplay) - 20;
+		u16 drq = (mode->hsync_start - mode->hdisplay) - 20;
 
 		drq *= mipi_dsi_pixel_format_to_bpp(device->format);
 		drq /= 32;
-- 
2.21.0


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  parent reply	other threads:[~2019-10-01  8:04 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-01  8:02 [PATCH 0/3] drm/sun4i: dsi: misc timing fixes Icenowy Zheng
2019-10-01  8:02 ` [PATCH 1/3] Revert "drm/sun4i: dsi: Change the start delay calculation" Icenowy Zheng
2019-10-03  7:08   ` [linux-sunxi] " Jagan Teki
2019-10-03 13:19     ` Maxime Ripard
2019-10-03 13:21       ` Icenowy Zheng
2019-10-03 13:34         ` Maxime Ripard
2019-10-01  8:02 ` Icenowy Zheng [this message]
2019-10-03  4:37   ` [linux-sunxi] [PATCH 2/3] drm/sun4i: dsi: fix DRQ calculation Jagan Teki
2019-10-01  8:02 ` [PATCH 3/3] Revert "drm/sun4i: dsi: Rework a bit the hblk calculation" Icenowy Zheng
2019-10-03  4:23   ` [linux-sunxi] " Jagan Teki
2019-10-06 14:44     ` Icenowy Zheng
2019-10-06 15:12       ` Icenowy Zheng
2019-10-07 15:19         ` Ondřej Jirman
2019-10-02 10:36 ` [PATCH 0/3] drm/sun4i: dsi: misc timing fixes Maxime Ripard
2019-10-03  3:58   ` Icenowy Zheng

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