linux-kernel - Re: [PATCH 01/10] drm/sun4i: sun6i_mipi_dsi: Compute burst mode loop N1 instruction delay

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Message-ID: <20181105103801.r6fo2qvmx6erx3zf@flea>
Date:   Mon, 5 Nov 2018 11:38:01 +0100
From:   Maxime Ripard <maxime.ripard@...tlin.com>
To:     Jagan Teki <jagan@...rulasolutions.com>
Cc:     Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...ux.ie>,
        Rob Herring <robh+dt@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
        Icenowy Zheng <icenowy@...c.io>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Vasily Khoruzhick <anarsoul@...il.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Mark Rutland <mark.rutland@....com>,
        dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Michael Trimarchi <michael@...rulasolutions.com>,
        TL Lim <tllim@...e64.org>, linux-sunxi@...glegroups.com
Subject: Re: [PATCH 01/10] drm/sun4i: sun6i_mipi_dsi: Compute burst mode loop
 N1 instruction delay

On Sat, Nov 03, 2018 at 03:38:51PM +0530, Jagan Teki wrote:
> Loop N1 instruction delay for burst mode lcd panel are
> computed as per BSP code.
> 
> Reference code is available in BSP
> (in drivers/video/sunxi/disp2/disp/de/lowlevel_sun50iw1/de_dsi.c)
> dsi_dev[sel]->dsi_inst_loop_num.bits.loop_n1=
> (panel->lcd_ht-panel->lcd_x)*(150)/(panel->lcd_dclk_freq*8) - 50;
> => (((mode->htotal - mode->hdisplay) * 150) / ((mode->clock / 1000) * 8)) - 50;
> 
> So use the similar computation for loop N1 delay.
> 
> Signed-off-by: Jagan Teki <jagan@...rulasolutions.com>
> ---
>  drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> index 86430efd9054..da152c21ec62 100644
> --- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> +++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> @@ -394,7 +394,14 @@ static void sun6i_dsi_setup_burst(struct sun6i_dsi *dsi,
>  static void sun6i_dsi_setup_inst_loop(struct sun6i_dsi *dsi,
>  				      struct drm_display_mode *mode)
>  {
> -	u16 delay = 50 - 1;
> +	struct mipi_dsi_device *device = dsi->device;
> +	u16 delay;
> +
> +	if (device->mode_flags == MIPI_DSI_MODE_VIDEO_BURST)
> +		delay = (((mode->htotal - mode->hdisplay) * 150) /
> +			((mode->clock / 1000) * 8)) - 50;
> +	else
> +		delay = 50 - 1;

Apart from the other comments, I'd really prefer to have a function
here that would take the mipi_dsi_device and compute the delay.

Maxime

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

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