linux-kernel - [PATCH v4 12/26] drm/sun4i: sun6i_mipi_dsi: Fix DSI hblk timing calculation

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Message-Id: <20181113111633.20189-13-jagan@amarulasolutions.com>
Date:   Tue, 13 Nov 2018 16:46:19 +0530
From:   Jagan Teki <jagan@...rulasolutions.com>
To:     Maxime Ripard <maxime.ripard@...tlin.com>,
        Chen-Yu Tsai <wens@...e.org>, Icenowy Zheng <icenowy@...c.io>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Vasily Khoruzhick <anarsoul@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        David Airlie <airlied@...ux.ie>,
        dri-devel@...ts.freedesktop.org,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, linux-clk@...r.kernel.org,
        Michael Trimarchi <michael@...rulasolutions.com>,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-sunxi@...glegroups.com,
        linux-amarula@...rulasolutions.com
Cc:     Jagan Teki <jagan@...rulasolutions.com>
Subject: [PATCH v4 12/26] drm/sun4i: sun6i_mipi_dsi: Fix DSI hblk timing calculation

hblk is adding line with all porch timing values, or timings
values from htotal without sync time.

Current driver is subtracting htotal with hsa, but the hsa
is bounded with packet overhead. For real hblk calculation
needed by subtracting htotal with back and front porch values
and BSP code BPI-M64-bsp is eventually following the same.

BPI-M64-bsp is computing hbp as (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);
=> (timmings->hor_total_time - timmings->hor_sync_time)
=> (mode->htotal - (mode->hsync_end - mode->hsync_start))

So, update the DSI hblk 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 | 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 de0992052a90..cd657ac4bdae 100644
--- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
+++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
@@ -495,7 +495,7 @@ static void sun6i_dsi_setup_timings(struct sun6i_dsi *dsi,
 	/*
 	 * hblk seems to be the line + porches length.
 	 */
-	hblk = mode->htotal * Bpp - hsa;
+	hblk = (mode->htotal - (mode->hsync_end - mode->hsync_start)) * Bpp;
 
 	/*
 	 * And I'm not entirely sure what vblk is about. The driver in
-- 
2.18.0.321.gffc6fa0e3