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

From: Thierry Reding
Date: Wed Jun 06 2018 - 06:39:14 EST


On Tue, Jun 05, 2018 at 11:19:14PM +0300, Dmitry Osipenko wrote:
> 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.

We don't really use a -controller suffix for any of the other
controllers because it is kind of implied. "nfc" is also not something
that is ever referred to in the technical documentation.

"nvidia,tegra20-nand" would be most consistent with all the rest of
Tegra (c.f. "nvidia,tegra*-ahci", "nvidia,tegra*-pci",
"nvidia,tegra*-hda", "nvidia,tegra*-gmi", ...).

Thierry

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