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

From: Maxime Ripard <maxime.ripard@bootlin.com>
To: Jagan Teki <jagan@amarulasolutions.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
	devicetree@vger.kernel.org,
	Jernej Skrabec <jernej.skrabec@siol.net>,
	David Airlie <airlied@linux.ie>,
	linux-sunxi@googlegroups.com, linux-kernel@vger.kernel.org,
	dri-devel@lists.freedesktop.org,
	Vasily Khoruzhick <anarsoul@gmail.com>,
	Chen-Yu Tsai <wens@csie.org>, Rob Herring <robh+dt@kernel.org>,
	Thierry Reding <thierry.reding@gmail.com>,
	TL Lim <tllim@pine64.org>,
	Michael Trimarchi <michael@amarulasolutions.com>,
	Sean Paul <sean@poorly.run>,
	linux-arm-kernel@lists.infradead.org,
	Icenowy Zheng <icenowy@aosc.io>
Subject: Re: [PATCH 01/10] drm/sun4i: sun6i_mipi_dsi: Compute burst mode loop N1 instruction delay
Date: Mon, 5 Nov 2018 11:38:01 +0100	[thread overview]
Message-ID: <20181105103801.r6fo2qvmx6erx3zf@flea> (raw)
In-Reply-To: <20181103100900.30313-2-jagan@amarulasolutions.com>

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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@amarulasolutions.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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