Thread (31 messages) 31 messages, 3 authors, 2019-01-08
STALE2708d
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[PATCH v5 10/17] drm/sun4i: sun6i_mipi_dsi: Add DSI hblk packet overhead

From: Jagan Teki <jagan@amarulasolutions.com>
Date: 2018-12-10 16:18:07
Also in: dri-devel, linux-clk, lkml
Subsystem: drm drivers, drm drivers and misc gpu patches, drm drivers for allwinner a10, the rest · Maintainers: David Airlie, Simona Vetter, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann, Chen-Yu Tsai, Linus Torvalds

Add 10 bytes packet overhead for hblk where blank is set using
a blanking packet like (4 bytes + 4 bytes + payload + 2 bytes)

This is according to BSP code from BPI-M64-bsp (from linux-sunxi/
drivers/video/sunxi/disp2/disp/de/lowlevel_sun50iw1/de_dsi.c)

dsi_hblk = (ht-hspw)*dsi_pixel_bits[format]/8-(4+4+2);

So, add 10 bytes packet overhead for DSI hblk.

Tested on 2-lane, 4-lane MIPI-DSI LCD panels.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
---
 drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
index 4c95b3384ed9..07eba9ec469b 100644
--- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
+++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
@@ -494,8 +494,13 @@ static void sun6i_dsi_setup_timings(struct sun6i_dsi *dsi,
 
 	/*
 	 * hblk seems to be the line + porches length.
+	 * The blank is set using a blanking packet (4 bytes + 4 bytes +
+	 * payload + 2 bytes). So minimal size is 10 bytes
 	 */
-	hblk = (mode->htotal - (mode->hsync_end - mode->hsync_start)) * Bpp;
+#define HBLK_PACKET_OVERHEAD	10
+	hblk = max((unsigned int)HBLK_PACKET_OVERHEAD,
+		   (mode->htotal - (mode->hsync_end - mode->hsync_start)) *
+		   Bpp - HBLK_PACKET_OVERHEAD);
 
 	/*
 	 * And I'm not entirely sure what vblk is about. The driver in
-- 
2.18.0.321.gffc6fa0e3


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