Re: [RFC PATCH v2 1/2] dt-bindings: nand: meson: add Amlogic NAND controller driver

[Boris Brezillon <boris.brezillon@bootlin.com>]

On Thu, 19 Jul 2018 17:46:11 +0800
Yixun Lan <yixun.lan@amlogic.com> wrote:

> From: Liang Yang <liang.yang@amlogic.com>
> 
> Add Amlogic NAND controller dt-bindings for Meson SoC,
> Current this driver support GXBB/GXL/AXG platform.
> 
> Signed-off-by: Liang Yang <liang.yang@amlogic.com>
> Signed-off-by: Yixun Lan <yixun.lan@amlogic.com>
> ---
>  .../bindings/mtd/amlogic,meson-nand.txt       | 95 +++++++++++++++++++
>  1 file changed, 95 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mtd/amlogic,meson-nand.txt
> 
> diff --git a/Documentation/devicetree/bindings/mtd/amlogic,meson-nand.txt b/Documentation/devicetree/bindings/mtd/amlogic,meson-nand.txt
> new file mode 100644
> index 000000000000..31f910dcd27a
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mtd/amlogic,meson-nand.txt
> @@ -0,0 +1,95 @@
> +Amlogic NAND Flash Controller (NFC) for GXBB/GXL/AXG family SoCs
> +
> +This file documents the properties in addition to those available in
> +the MTD NAND bindings.
> +
> +Required properties:
> +- compatible : contains one of:
> +  - "amlogic,meson-gxl-nfc"
> +  - "amlogic,meson-axg-nfc"
> +- clocks     :
> +	A list of phandle + clock-specifier pairs for the clocks listed
> +	in clock-names.
> +
> +- clock-names: Should contain the following:
> +	"core" - NFC module gate clock
> +	"device" - device clock from eMMC sub clock controller
> +
> +- pins     : Select pins which NFC need.
> +- nand_pins: Detail NAND pins information.

You should document pinctrl-0 and pinctrl-names, not pins and nand_pins.

> +- amlogic,mmc-syscon	: Required for NAND clocks, it's shared with SD/eMMC
> +				controller port C

Are you sure this is still needed, even after exposing MMC/NAND clks
through the CCF?

You forgot
- #address-cells
- #size-cells
- reg
- interrupts
- 

> +
> +Optional children nodes:
> +Children nodes represent the available nand chips.
> +
> +Optional properties:
> +- amlogic,nand-enable-scrambler: enable the NAND scrambler feature.
> +	- (absent) = scrambler is disabled
> +	- (present) = scrambler is enabled

I keep thinking this is not needed if you have the NAND chip properly
defined (NAND_NEED_SCRAMBLING flag set in chip->options).

> +
> +
> +Other properties:
> +see Documentation/devicetree/bindings/mtd/nand.txt for generic bindings.
> +
> +Example demonstrate on AXG SoC:
> +
> +	sd_emmc_c_clkc: mmc@7000 {
> +		compatible = "amlogic,meson-axg-mmc-clkc", "syscon";
> +		reg = <0x0 0x7000 0x0 0x800>;
> +		status = "okay";
> +	};
> +
> +	nand: nfc@7800 {
> +		compatible = "amlogic,meson-axg-nfc";
> +		reg = <0x0 0x7800 0x0 0x100>;
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +		interrupts = <GIC_SPI 34 IRQ_TYPE_EDGE_RISING>;
> +		status = "disabled";
> +
> +		clocks = <&clkc CLKID_SD_EMMC_C>,
> +			<&sd_emmc_c_clkc CLKID_MMC_DIV>;
> +		clock-names = "core", "device";
> +		amlogic,mmc-syscon = <&sd_emmc_c_clkc>;
> +
> +		status = "okay";
> +
> +		pinctrl-names = "default";
> +		pinctrl-0 = <&nand_pins>;
> +
> +		nand@0 {
> +			reg = <0>;
> +			#address-cells = <1>;
> +			#size-cells = <1>;
> +
> +			nand-on-flash-bbt;
> +			nand-ecc-mode = "hw";
> +			nand-ecc-strength = <8>;
> +			nand-ecc-step-size = <1024>;

I'd recommend not forcing a specific ECC config in the example.

> +
> +			amlogic,nand-enable-scrambler;
> +
> +			partition@0 {
> +				label = "boot";
> +				reg = <0x00000000 0x00200000>;
> +				read-only;
> +			};

Blank line here.

> +			partition@200000 {
> +				label = "env";
> +				reg = <0x00200000 0x00400000>;
> +			};
> +			partition@600000 {
> +				label = "system";
> +				reg = <0x00600000 0x00a00000>;
> +			};
> +			partition@1000000 {
> +				label = "rootfs";
> +				reg = <0x01000000 0x03000000>;
> +			};
> +			partition@4000000 {
> +				label = "media";
> +				reg = <0x04000000 0x8000000>;
> +			};
> +		};
> +	};