linux-kernel - [PATCH v5 09/17] drm/sun4i: sun6i_mipi_dsi: Fix DSI hblk timing calculation

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Date:   Mon, 10 Dec 2018 21:47:21 +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 09/17] 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 81151d7633f9..4c95b3384ed9 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