linux-kernel - Re: [PATCH V2 3/3] ARM: davinci: da850: add NAND driver entries

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Date:	Wed, 9 Jan 2013 18:17:46 +0530
From:	Sekhar Nori <nsekhar@...com>
To:	"Kumar, Anil" <anilkumar.v@...com>
CC:	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>,
	<davinci-linux-open-source@...ux.davincidsp.com>,
	<linux@....linux.org.uk>,
	Kevin Hilman <khilman@...prootsystems.com>, <hs@...x.de>
Subject: Re: [PATCH V2 3/3] ARM: davinci: da850: add NAND driver entries

On 1/8/2013 1:50 PM, Kumar, Anil wrote:
> Add NAND driver entries to export NAND functionality on da850 EVM and
> NAND pinctrl node to do pin mux according to pinctrl-single driver.

Subject line should have DT and da850 evm somewhere.
Otherwise NAND has been supported on DA850 for long.

> 
> Signed-off-by: Kumar, Anil <anilkumar.v@...com>
> ---
> :100644 100644 c7609d0... 382a7da... M	arch/arm/boot/dts/da850-evm.dts
> :100644 100644 e9c6e82... 16e2ac2... M	arch/arm/boot/dts/da850.dtsi
>  arch/arm/boot/dts/da850-evm.dts |   19 +++++++++++++++++++
>  arch/arm/boot/dts/da850.dtsi    |   13 +++++++++++++
>  2 files changed, 32 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/arm/boot/dts/da850-evm.dts b/arch/arm/boot/dts/da850-evm.dts
> index c7609d0..382a7da 100644
> --- a/arch/arm/boot/dts/da850-evm.dts
> +++ b/arch/arm/boot/dts/da850-evm.dts
> @@ -28,4 +28,23 @@
>  			status = "okay";
>  		};
>  	};
> +	nand_cs3@...00000 {
> +		status = "okay";
> +	};
> +};
> +&pmx_core{
> +	pinctrl-names = "default";
> +	pinctrl-0 = <
> +		&nand_cs3_pins
> +	>;

This means that the NAND pins are configured even if NAND is not
probed. Right? This can be moved into the nand_cs3 node to avoid that. 
And then when used with Linus Walleij's patch "drivers/pinctrl: grab 
default handles from device core" which should be accepted soon, the 
pins will be automatically setup when the NAND gets probed.

> +
> +	nand_cs3_pins: pinmux_nand_pins {
> +		pinctrl-single,bits = <
> +			0x1c 0x00110000  0x00ff0000     /* EMA_OE, EMA_WE */
> +			0x1c 0x00000110  0x00000ff0     /* EMA_CS[4],EMA_CS[3]*/
> +			0x24 0x11111111  0xffffffff     /* EMA_D[0], EMA_D[1], EMA_D[2], EMA_D[3],
> +							   EMA_D[4], EMA_D[5], EMA_D[6], EMA_D[7] */
> +			0x30 0x01100000  0x0ff00000     /* EMA_A[1], EMA_A[2] */
> +		>;
> +	};

I suspect a number of other boards using NAND on CS3 would have to 
repeat these configurations. It will be better to move them into the 
da850.dtsi file so it can be reused.

Since I am new to the DT and pinctrl stuff, I had to actually try these to 
make sure what I am suggesting isn't nonsense. I came up with this 
patch on top of your series. Please test it at your end and also see if you 
are happy with the changes.

Thanks,
Sekhar

---8<----
diff --git a/arch/arm/boot/dts/da850-evm.dts b/arch/arm/boot/dts/da850-evm.dts
index 382a7da..52abb9d 100644
--- a/arch/arm/boot/dts/da850-evm.dts
+++ b/arch/arm/boot/dts/da850-evm.dts
@@ -30,21 +30,8 @@
 	};
 	nand_cs3@...00000 {
 		status = "okay";
+		pinctrl-names = "default";
+		pinctrl-0 = <&nand_cs3_pins>;
 	};
 };
-&pmx_core{
-	pinctrl-names = "default";
-	pinctrl-0 = <
-		&nand_cs3_pins
-	>;
 
-	nand_cs3_pins: pinmux_nand_pins {
-		pinctrl-single,bits = <
-			0x1c 0x00110000  0x00ff0000     /* EMA_OE, EMA_WE */
-			0x1c 0x00000110  0x00000ff0     /* EMA_CS[4],EMA_CS[3]*/
-			0x24 0x11111111  0xffffffff     /* EMA_D[0], EMA_D[1], EMA_D[2], EMA_D[3],
-							   EMA_D[4], EMA_D[5], EMA_D[6], EMA_D[7] */
-			0x30 0x01100000  0x0ff00000     /* EMA_A[1], EMA_A[2] */
-		>;
-	};
-};
diff --git a/arch/arm/boot/dts/da850.dtsi b/arch/arm/boot/dts/da850.dtsi
index 6ab9730..c4b21a8 100644
--- a/arch/arm/boot/dts/da850.dtsi
+++ b/arch/arm/boot/dts/da850.dtsi
@@ -38,7 +38,25 @@
 			pinctrl-single,register-width = <32>;
 			pinctrl-single,function-mask = <0xffffffff>;
 			status = "disabled";
+
+			nand_cs3_pins: pinmux_nand_pins {
+				pinctrl-single,bits = <
+					/* EMA_OE, EMA_WE */
+					0x1c 0x00110000  0x00ff0000
+					/* EMA_CS[4],EMA_CS[3]*/
+					0x1c 0x00000110  0x00000ff0
+					/*
+					 * EMA_D[0], EMA_D[1], EMA_D[2],
+					 * EMA_D[3], EMA_D[4], EMA_D[5],
+					 * EMA_D[6], EMA_D[7]
+					 */
+					0x24 0x11111111  0xffffffff
+					/* EMA_A[1], EMA_A[2] */
+					0x30 0x01100000  0x0ff00000
+				>;
+			};
 		};
+
 		serial0: serial@...2000 {
 			compatible = "ns16550a";
 			reg = <0x42000 0x100>;
--
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