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[v7,21/23] drm/sun4i: sun6i_mipi_dsi: Fix DSI hbp timing value

Message ID 20190201154232.10505-22-jagan@amarulasolutions.com (mailing list archive)
State Not Applicable, archived
Headers show
Series drm/sun4i: Allwinner A64 MIPI-DSI support | expand

Commit Message

Jagan Teki Feb. 1, 2019, 3:42 p.m. UTC 
Current driver is calculating hbp maximum value by subtracting
hsync_start with hdisplay which is front porch value, but the
hbp refers to back porch.

Back porch value is calculating by subtracting htotal with
hsync_end as per drm_mode timings, and BSP code from BPI-M64-bsp
is eventually following the same.

BPI-M64-bsp is computing hbp as
(in drivers/video/sunxi/disp2/disp/de/lowlevel_sun50iw1/de_dsi.c)
dsi_hbp = (hbp-hspw)*dsi_pixel_bits[format]/8 - (4+2);
=> (panel->lcd_hbp - timmings->hor_sync_time)
=> (timmings->hor_back_porch + timmings->hor_sync_time -
    timmings->hor_sync_time)
=> timmings->hor_back_porch
=> mode->htotal - mode->hsync_end

So, update the MIPI-DSI hbp value accordingly.

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

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Tested-by: Merlijn Wajer <merlijn@wizzup.org>
---
 drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
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Patch

diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
index 09569938c20d..780b1906c661 100644
--- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
+++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
@@ -579,7 +579,7 @@  static void sun6i_dsi_setup_timings(struct sun6i_dsi *dsi,
 	 */
 #define HBP_PACKET_OVERHEAD	6
 	hbp = max((unsigned int)HBP_PACKET_OVERHEAD,
-		  (mode->hsync_start - mode->hdisplay) * Bpp - HBP_PACKET_OVERHEAD);
+		  (mode->htotal - mode->hsync_end) * Bpp - HBP_PACKET_OVERHEAD);
 
 	/*
 	 * The frontporch is set using a blanking packet (4 bytes +