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Message-Id: <20181210161729.29720-12-jagan@amarulasolutions.com>
Date: Mon, 10 Dec 2018 21:47:23 +0530
From: Jagan Teki <jagan@...rulasolutions.com>
To: Maxime Ripard <maxime.ripard@...tlin.com>,
Chen-Yu Tsai <wens@...e.org>,
Michael Turquette <mturquette@...libre.com>,
Stephen Boyd <sboyd@...nel.org>
Cc: linux-arm-kernel@...ts.infradead.org, linux-clk@...r.kernel.org,
linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
Michael Trimarchi <michael@...rulasolutions.com>,
linux-sunxi <linux-sunxi@...glegroups.com>,
linux-amarula@...rulasolutions.com,
Jagan Teki <jagan@...rulasolutions.com>
Subject: [PATCH v5 11/17] drm/sun4i: sun6i_mipi_dsi: Fix DSI hfp timing value
Current driver is calculating hfp maximum value by subtracting
htotal with hsync_end which is front back value, but the
hpp refers to front porch.
Front porch value is calculating by subtracting hsync_start with
hdisplay as per drm_mode timings, and BSP code from BPI-M64-bsp
is eventually following the same.
BPI-M64-bsp is computing hfp as (from linux-sunxi/
drivers/video/sunxi/disp2/disp/de/lowlevel_sun50iw1/de_dsi.c)
dsi_hbp = (hbp-hspw)*dsi_pixel_bits[format]/8 - (4+2);
dsi_hact = x * dsi_pixel_bits[format]/8;
dsi_hblk = (ht-hspw)*dsi_pixel_bits[format]/8-(4+4+2);
dsi_hfp = dsi_hblk - (4+dsi_hact+2) - (4+dsi_hbp+2);
Example,
u32 fmt = dsi_pixel_bits[format]/8;
=> ((ht-hspw)*fmt - 10) - (6 + x * fmt) - (6 + (hbp-hspw)*fmt - 6)
=> (ht - hspw - x - (hbp - hspw)) * fmt - 16
=> (ht - x - hbp) * fmt - 16
=> (ht - x - (timmings->hor_total_time - timmings->hor_front_porch - x)
* fmt - 16
=> (timmings->hor_total_time - x - timmings->hor_total_time +
timmings->hor_front_porch + x) * fmt - 16
=> timmings->hor_front_porch * fmt - 16
So, update the DSI hfp timing accordingly.
Tested on 2-lane, 4-lane MIPI-DSI LCD panels.
Signed-off-by: Jagan Teki <jagan@...rulasolutions.com>
---
drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
index 07eba9ec469b..d8947be92f9d 100644
--- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
+++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
@@ -490,7 +490,8 @@ static void sun6i_dsi_setup_timings(struct sun6i_dsi *dsi,
*/
#define HFP_PACKET_OVERHEAD 6
hfp = max((unsigned int)HFP_PACKET_OVERHEAD,
- (mode->htotal - mode->hsync_end) * Bpp - HFP_PACKET_OVERHEAD);
+ (mode->hsync_start - mode->hdisplay) * Bpp -
+ HFP_PACKET_OVERHEAD);
/*
* hblk seems to be the line + porches length.
--
2.18.0.321.gffc6fa0e3
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