linux-kernel - Re: [PATCH 2/2] ARM: DT: tegra: pinctrl suspend resume hook

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Message-ID: <20130426194908.GA3302@avionic-0098.mockup.avionic-design.de>
Date:	Fri, 26 Apr 2013 21:49:08 +0200
From:	Thierry Reding <thierry.reding@...onic-design.de>
To:	Bibek Basu <bbasu@...dia.com>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>, linus.walleij@...aro.org,
	swarren@...dotorg.org, linux-tegra@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH 2/2] ARM: DT: tegra: pinctrl suspend resume hook

On Tue, Apr 23, 2013 at 11:39:02PM +0530, Bibek Basu wrote:
> Make pinmux as the first node of tegra DT
> so as to achieve pinctrl as last device to suspend and
> first device to resume.

I don't think this is a good idea. For one it encodes Linux specific
implementation details within the device tree. Furthermore I seem to
remember that the device tree makes no guarantees that the order of
nodes in the blob is the same as the order in the DTS.

That said I don't have a good alternative. Perhaps one solution would be
to use suspend_late() and resume_early() for the pinmux driver since
they will be called after and before the suspend() and resume()
callbacks of all other devices, respectively. Other than that I wasn't
able to find anything about forcing a particular order during suspend
and resume.

Cc'ing Rafael and the linux-pm mailing list, maybe somebody among them
knows a proper solution.

Thierry

> 
> Signed-off-by: Bibek Basu <bbasu@...dia.com>
> ---
>  arch/arm/boot/dts/tegra114.dtsi | 12 ++++++------
>  arch/arm/boot/dts/tegra20.dtsi  | 16 ++++++++--------
>  arch/arm/boot/dts/tegra30.dtsi  | 13 +++++++------
>  3 files changed, 21 insertions(+), 20 deletions(-)
> 
> diff --git a/arch/arm/boot/dts/tegra114.dtsi b/arch/arm/boot/dts/tegra114.dtsi
> index a58a761..36596ae 100644
> --- a/arch/arm/boot/dts/tegra114.dtsi
> +++ b/arch/arm/boot/dts/tegra114.dtsi
> @@ -11,6 +11,12 @@
>  		serial3 = &uartd;
>  	};
>  
> +	pinmux: pinmux {
> +		compatible = "nvidia,tegra114-pinmux";
> +		reg = <0x70000868 0x148		/* Pad control registers */
> +		       0x70003000 0x40c>;	/* Mux registers */
> +	};
> +
>  	host1x {
>  		compatible = "nvidia,tegra114-host1x", "simple-bus";
>  		reg = <0x50000000 0x00028000>;
> @@ -165,12 +171,6 @@
>  		interrupt-controller;
>  	};
>  
> -	pinmux: pinmux {
> -		compatible = "nvidia,tegra114-pinmux";
> -		reg = <0x70000868 0x148		/* Pad control registers */
> -		       0x70003000 0x40c>;	/* Mux registers */
> -	};
> -
>  	/*
>  	 * There are two serial driver i.e. 8250 based simple serial
>  	 * driver and APB DMA based serial driver for higher baudrate
> diff --git a/arch/arm/boot/dts/tegra20.dtsi b/arch/arm/boot/dts/tegra20.dtsi
> index a5a9615..6d8a663 100644
> --- a/arch/arm/boot/dts/tegra20.dtsi
> +++ b/arch/arm/boot/dts/tegra20.dtsi
> @@ -12,6 +12,14 @@
>  		serial4 = &uarte;
>  	};
>  
> +	pinmux: pinmux {
> +		compatible = "nvidia,tegra20-pinmux";
> +		reg = <0x70000014 0x10   /* Tri-state registers */
> +		       0x70000080 0x20   /* Mux registers */
> +		       0x700000a0 0x14   /* Pull-up/down registers */
> +		       0x70000868 0xa8>; /* Pad control registers */
> +	};
> +
>  	host1x {
>  		compatible = "nvidia,tegra20-host1x", "simple-bus";
>  		reg = <0x50000000 0x00024000>;
> @@ -196,14 +204,6 @@
>  		interrupt-controller;
>  	};
>  
> -	pinmux: pinmux {
> -		compatible = "nvidia,tegra20-pinmux";
> -		reg = <0x70000014 0x10   /* Tri-state registers */
> -		       0x70000080 0x20   /* Mux registers */
> -		       0x700000a0 0x14   /* Pull-up/down registers */
> -		       0x70000868 0xa8>; /* Pad control registers */
> -	};
> -
>  	das {
>  		compatible = "nvidia,tegra20-das";
>  		reg = <0x70000c00 0x80>;
> diff --git a/arch/arm/boot/dts/tegra30.dtsi b/arch/arm/boot/dts/tegra30.dtsi
> index 9f33086..b4b79f0 100644
> --- a/arch/arm/boot/dts/tegra30.dtsi
> +++ b/arch/arm/boot/dts/tegra30.dtsi
> @@ -12,6 +12,13 @@
>  		serial4 = &uarte;
>  	};
>  
> +	pinmux: pinmux {
> +		compatible = "nvidia,tegra30-pinmux";
> +		reg = <0x70000868 0xd4    /* Pad control registers */
> +		       0x70003000 0x3e4>; /* Mux registers */
> +	};
> +
> +
>  	host1x {
>  		compatible = "nvidia,tegra30-host1x", "simple-bus";
>  		reg = <0x50000000 0x00024000>;
> @@ -216,12 +223,6 @@
>  		interrupt-controller;
>  	};
>  
> -	pinmux: pinmux {
> -		compatible = "nvidia,tegra30-pinmux";
> -		reg = <0x70000868 0xd4    /* Pad control registers */
> -		       0x70003000 0x3e4>; /* Mux registers */
> -	};
> -
>  	/*
>  	 * There are two serial driver i.e. 8250 based simple serial
>  	 * driver and APB DMA based serial driver for higher baudrate
> -- 
> 1.8.1.5
> 
> --
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