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SubjectRe: [PATCH v9 2/5] drm/sun4i: sun6i_mipi_dsi: Fix TCON DRQ set bits
On Sun, Mar 03, 2019 at 11:05:24PM +0530, Jagan Teki wrote:
> TCON DRQ for non-burst DSI mode can computed based on horizontal
> front porch value, but the current driver trying to include sync
> timings along with front porch resulting wrong drq.
>
> This patch is trying to update the drq by subtracting hsync_start
> with hdisplay, which is horizontal front porch.
>
> Current code:
> ------------
> mode->hsync_end - mode->hdisplay => horizontal front porch + sync
>
> With this patch:
> ----------------
> mode->hsync_start - mode->hdisplay => horizontal front porch
>
> BSP code form BPI-M64-bsp is computing TCON DRQ set bits
> for non-burts as (from linux-sunxi/
> drivers/video/sunxi/disp2/disp/de/lowlevel_sun50iw1/de_dsi.c)
>
> => panel->lcd_ht - panel->lcd_x - panel->lcd_hbp
> => (timmings->hor_front_porch + panel->lcd_hbp + panel->lcd_x)
^ + sync length +
> - panel->lcd_x - panel->hbp
> => timmings->hor_front_porch
^ + sync
> => mode->hsync_start - mode->hdisplay

s/hsync_start/hsync_end/

Did you encounter any panel where this was fixing something? If so,
which one, and what is the matching timings and / or datasheet?

Maxime

--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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