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Date:   Thu, 27 Sep 2018 17:21:26 +0200
From:   Maxime Ripard <maxime.ripard@bootlin.com>
To:     Jagan Teki <jagan@amarulasolutions.com>
Cc:     Chen-Yu Tsai <wens@csie.org>, Icenowy Zheng <icenowy@aosc.io>,
        Jernej Skrabec <jernej.skrabec@siol.net>,
        Vasily Khoruzhick <anarsoul@gmail.com>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        David Airlie <airlied@linux.ie>,
        dri-devel@lists.freedesktop.org,
        Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@kernel.org>, linux-clk@vger.kernel.org,
        Michael Trimarchi <michael@amarulasolutions.com>,
        linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-sunxi@googlegroups.com
Subject: Re: [PATCH 06/12] drm/sun4i: sun6i_mipi_dsi: Fix VBP size calculation
Message-ID: <20180927152126.vovnvwmqdfpuxgdm@flea>
References: <20180927114850.24565-1-jagan@amarulasolutions.com>
 <20180927114850.24565-7-jagan@amarulasolutions.com>
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On Thu, Sep 27, 2018 at 05:18:44PM +0530, Jagan Teki wrote:
> According to horizontal and vertical timings are defined
> per the diagram from include/drm/drm_modes.h
> 
> Back porch = [hv]total - [hv]sync_end
>
> So, update SUN6I_DSI_BASIC_SIZE0_VBP calculation as
> mode->vtotal - mode->vsync_end
> 
> Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
> ---
>  drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> index 1c7e42015645..599284971ab6 100644
> --- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> +++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> @@ -526,8 +526,8 @@ static void sun6i_dsi_setup_timings(struct sun6i_dsi *dsi,
>  	regmap_write(dsi->regs, SUN6I_DSI_BASIC_SIZE0_REG,
>  		     SUN6I_DSI_BASIC_SIZE0_VSA(mode->vsync_end -
>  					       mode->vsync_start) |
> -		     SUN6I_DSI_BASIC_SIZE0_VBP(mode->vsync_start -
> -					       mode->vdisplay));
> +		     SUN6I_DSI_BASIC_SIZE0_VBP(mode->vtotal -
> +					       mode->vsync_end));

Is it purely theoretical, or did you find some source that back that?

Maxime

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