Re: [PATCH v3 3/6] mtd: rawnand: tegra: add devicetree binding

[Dmitry Osipenko]

On 01.06.2018 10:30, Boris Brezillon wrote:
> On Fri,  1 Jun 2018 00:16:34 +0200
> Stefan Agner <stefan@xxxxxxxx> wrote:
> 
>> This adds the devicetree binding for the Tegra 2 NAND flash
>> controller.
>>
>> Signed-off-by: Lucas Stach <dev@xxxxxxxxxx>
>> Signed-off-by: Stefan Agner <stefan@xxxxxxxx>
>> ---
>>  .../bindings/mtd/nvidia-tegra20-nand.txt      | 64 +++++++++++++++++++
>>  1 file changed, 64 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/mtd/nvidia-tegra20-nand.txt
>>
>> diff --git a/Documentation/devicetree/bindings/mtd/nvidia-tegra20-nand.txt b/Documentation/devicetree/bindings/mtd/nvidia-tegra20-nand.txt
>> new file mode 100644
>> index 000000000000..5cd984ef046b
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/mtd/nvidia-tegra20-nand.txt
>> @@ -0,0 +1,64 @@
>> +NVIDIA Tegra NAND Flash controller
>> +
>> +Required properties:
>> +- compatible: Must be one of:
>> +  - "nvidia,tegra20-nand"
> 
> As discussed previously, I prefer "nvidia,tegra20-nand-controller" or
> "nvidia,tegra20-nfc".
> 
>> +- reg: MMIO address range
>> +- interrupts: interrupt output of the NFC controller
>> +- clocks: Must contain an entry for each entry in clock-names.
>> +  See ../clocks/clock-bindings.txt for details.
>> +- clock-names: Must include the following entries:
>> +  - nand
>> +- resets: Must contain an entry for each entry in reset-names.
>> +  See ../reset/reset.txt for details.
>> +- reset-names: Must include the following entries:
>> +  - nand
>> +
>> +Optional children nodes:
>> +Individual NAND chips are children of the NAND controller node. Currently
>> +only one NAND chip supported.
>> +
>> +Required children node properties:
>> +- reg: An integer ranging from 1 to 6 representing the CS line to use.
>> +
>> +Optional children node properties:
>> +- nand-ecc-mode: String, operation mode of the NAND ecc mode. Currently only
>> +		 "hw" is supported.
>> +- nand-ecc-algo: string, algorithm of NAND ECC.
>> +		 Supported values with "hw" ECC mode are: "rs", "bch".
>> +- nand-bus-width : See nand.txt
>> +- nand-on-flash-bbt: See nand.txt
>> +- nand-ecc-strength: integer representing the number of bits to correct
>> +		     per ECC step (always 512). Supported strength using HW ECC
>> +		     modes are:
>> +		     - RS: 4, 6, 8
>> +		     - BCH: 4, 8, 14, 16
>> +- nand-ecc-maximize: See nand.txt
>> +- nand-is-boot-medium: Makes sure only ECC strengths supported by the boot ROM
>> +		       are choosen.
>> +- wp-gpios: GPIO specifier for the write protect pin.
>> +
>> +Optional child node of NAND chip nodes:
>> +Partitions: see partition.txt
>> +
>> +  Example:
>> +	nand@70008000 {
> 
> 	nand-controller@70008000 {
> 
>> +		compatible = "nvidia,tegra20-nand";
> 
> 		compatible = "nvidia,tegra20-nand-controller";
> 
> or
> 
> 		compatible = "nvidia,tegra20-nfc";
> 

Maybe it's just me, but when I'm reading "nfc", my first association is the
"Near Field Communication". Probably an explicit
"nvidia,tegra20-nand-controller" variant is more preferable.

>> +		reg = <0x70008000 0x100>;
>> +		interrupts = <GIC_SPI 24 IRQ_TYPE_LEVEL_HIGH>;
>> +		clocks = <&tegra_car TEGRA20_CLK_NDFLASH>;
>> +		clock-names = "nand";
>> +		resets = <&tegra_car 13>;
>> +		reset-names = "nand";
>> +
>> +		nand-chip@0 {
> 
> 		nand@0 {
> 
>> +			reg = <0>;
>> +			#address-cells = <1>;
>> +			#size-cells = <1>;
>> +			nand-bus-width = <8>;
>> +			nand-on-flash-bbt;
>> +			nand-ecc-algo = "bch";
>> +			nand-ecc-strength = <8>;
>> +			wp-gpios = <&gpio TEGRA_GPIO(S, 0) GPIO_ACTIVE_LOW>;
>> +		};
>> +	};
> 
> With this addressed,
> 
> Reviewed-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxx>
>