Re: [RFC PATCH v3 1/2] dt-bindings: nand: meson: add Amlogic NAND controller driver

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Hi boric,

Thanks for your quick reply.

On 9/7/2018 8:19 PM, Boris Brezillon wrote:
On Fri, 7 Sep 2018 18:57:10 +0800
Jianxin Pan <jianxin.pan@xxxxxxxxxxx> wrote:

From: Liang Yang <liang.yang@xxxxxxxxxxx>

Add Amlogic NAND controller dt-bindings for Meson SoC,
Current this driver support GXBB/GXL/AXG platform.

Signed-off-by: Liang Yang <liang.yang@xxxxxxxxxxx>
Signed-off-by: Yixun Lan <yixun.lan@xxxxxxxxxxx>
---
  .../devicetree/bindings/mtd/amlogic,meson-nand.txt | 91 ++++++++++++++++++++++
  1 file changed, 91 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 0000000..655a778
--- /dev/null
+++ b/Documentation/devicetree/bindings/mtd/amlogic,meson-nand.txt
@@ -0,0 +1,91 @@
+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 mean pinctrl-names and pinctrl-0, right? Not sure it's necessary to
document that, but if you do, please use the correct DT prop names.


I find no documentation for that in other xx_nand.txt; I will consider to remove it.

+- amlogic,mmc-syscon	: Required for NAND clocks, it's shared with SD/eMMC
+				controller port C
+
+Optional children nodes:
+Children nodes represent the available nand chips.
+
+
+

One too many blank lines here.

ok, i will remove it.

+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>;

Drop nand-ecc- props. I guess you have a sensible default value and I
prefer when ECC requirements are directly extracted during chip
detection. Defining that in the DT is a bad habit. The only one that
could make sense (assuming you support it) is nand-ecc-maximize.

ok, i will drop them.
we adopt auto detection during init stage, it works too.

+
+			amlogic,nand-enable-scrambler;

Please drop this property (it's not longer documented).

em, we should have removed it when nfc driver never use it.

+
+			partition@0 {
+				label = "boot";
+				reg = <0x00000000 0x00200000>;
+				read-only;
+			};
+			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>;
+			};

No need to define the partitions in your example, especially since they
should be placed in a partitions subnode with a "fixed-partitions"
compat.


ok, i will remove it.

+		};
+	};

.


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