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Message-Id: <20190124195900.22620-21-jagan@amarulasolutions.com>
Date: Fri, 25 Jan 2019 01:28:58 +0530
From: Jagan Teki <jagan@...rulasolutions.com>
To: Maxime Ripard <maxime.ripard@...tlin.com>,
David Airlie <airlied@...ux.ie>,
Daniel Vetter <daniel@...ll.ch>, Chen-Yu Tsai <wens@...e.org>,
Michael Turquette <mturquette@...libre.com>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-clk@...r.kernel.org, dri-devel@...ts.freedesktop.org,
devicetree@...r.kernel.org,
Michael Trimarchi <michael@...rulasolutions.com>,
linux-amarula@...rulasolutions.com, linux-sunxi@...glegroups.com,
Jagan Teki <jagan@...rulasolutions.com>
Subject: [PATCH v6 20/22] drm/sun4i: sun6i_mipi_dsi: Fix DSI hbp timing value
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@...rulasolutions.com>
---
drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
index 58bda0928aef..e24719cabba2 100644
--- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
+++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
@@ -578,7 +578,7 @@ 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 +
--
2.18.0.321.gffc6fa0e3
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