linux-kernel - Re: [PATCH 06/15] drm/sun4i: tcon: Add support for tcon-top

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Date:   Mon, 21 May 2018 10:07:59 +0200
From:   Maxime Ripard <maxime.ripard@...tlin.com>
To:     Jernej Skrabec <jernej.skrabec@...l.net>
Cc:     wens@...e.org, robh+dt@...nel.org, mark.rutland@....com,
        dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-sunxi@...glegroups.com
Subject: Re: [PATCH 06/15] drm/sun4i: tcon: Add support for tcon-top

On Sat, May 19, 2018 at 08:31:18PM +0200, Jernej Skrabec wrote:
> If SoC has TCON TOP unit, it has to be configured from TCON, since it
> has all information needed. Additionally, if it is TCON TV, it must also
> enable bus gate inside TCON TOP unit.

Why?

> Add support for such TCONs.
> 
> Signed-off-by: Jernej Skrabec <jernej.skrabec@...l.net>
> ---
>  drivers/gpu/drm/sun4i/sun4i_tcon.c | 28 ++++++++++++++++++++++++++++
>  drivers/gpu/drm/sun4i/sun4i_tcon.h |  8 ++++++++
>  2 files changed, 36 insertions(+)
> 
> diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> index 08747fc3ee71..e0c562ce1c22 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
> +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> @@ -688,6 +688,16 @@ static int sun4i_tcon_init_clocks(struct device *dev,
>  		dev_err(dev, "Couldn't get the TCON bus clock\n");
>  		return PTR_ERR(tcon->clk);
>  	}
> +
> +	if (tcon->quirks->needs_tcon_top && tcon->quirks->has_channel_1) {
> +		tcon->top_clk = devm_clk_get(dev, "tcon-top");
> +		if (IS_ERR(tcon->top_clk)) {
> +			dev_err(dev, "Couldn't get the TCON TOP bus clock\n");
> +			return PTR_ERR(tcon->top_clk);
> +		}
> +		clk_prepare_enable(tcon->top_clk);
> +	}
> +
>  	clk_prepare_enable(tcon->clk);
>  
>  	if (tcon->quirks->has_channel_0) {
> @@ -712,6 +722,7 @@ static int sun4i_tcon_init_clocks(struct device *dev,
>  static void sun4i_tcon_free_clocks(struct sun4i_tcon *tcon)
>  {
>  	clk_disable_unprepare(tcon->clk);
> +	clk_disable_unprepare(tcon->top_clk);
>  }
>  
>  static int sun4i_tcon_init_irq(struct device *dev,
> @@ -980,6 +991,23 @@ static int sun4i_tcon_bind(struct device *dev, struct device *master,
>  	tcon->id = engine->id;
>  	tcon->quirks = of_device_get_match_data(dev);
>  
> +	if (tcon->quirks->needs_tcon_top) {
> +		struct device_node *np;
> +
> +		np = of_parse_phandle(dev->of_node, "allwinner,tcon-top", 0);
> +		if (np) {
> +			struct platform_device *pdev;
> +
> +			pdev = of_find_device_by_node(np);
> +			if (pdev)
> +				tcon->tcon_top = platform_get_drvdata(pdev);
> +			of_node_put(np);
> +
> +			if (!tcon->tcon_top)
> +				return -EPROBE_DEFER;
> +		}
> +	}
> +

I might have missed it, but I've not seen the bindings additions for
that property. This shouldn't really be done that way anyway, instead
of using a direct phandle, you should be using the of-graph, with the
TCON-top sitting where it belongs in the flow of data.

Maxime

-- 
Maxime Ripard, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com

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