Re: [PATCH] mtd: s3c2410: add device tree support

[Mark Rutland <mark.rutland@arm.com>]

On Sat, Sep 17, 2016 at 12:22:40PM -0300, Sergio Prado wrote:
> Tested on FriendlyARM Mini2440
> 
> Signed-off-by: Sergio Prado <sergio.prado@e-labworks.com>
> ---
>  .../devicetree/bindings/mtd/samsung-s3c2410.txt    |  70 +++++++++++
>  drivers/mtd/nand/s3c2410.c                         | 129 ++++++++++++++++++++-
>  include/linux/platform_data/mtd-nand-s3c2410.h     |   1 +
>  3 files changed, 195 insertions(+), 5 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/mtd/samsung-s3c2410.txt
> 
> diff --git a/Documentation/devicetree/bindings/mtd/samsung-s3c2410.txt b/Documentation/devicetree/bindings/mtd/samsung-s3c2410.txt
> new file mode 100644
> index 000000000000..1c39f6cf483b
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mtd/samsung-s3c2410.txt
> @@ -0,0 +1,70 @@
> +* Samsung S3C2410 and compatible NAND flash controller
> +
> +Required properties:
> +- compatible : The possible values are:
> +	"samsung,s3c2410-nand"
> +	"samsung,s3c2412-nand"
> +	"samsung,s3c2440-nand"
> +	"samsung,s3c6400-nand"
> +- reg : register's location and length.
> +- #address-cells, #size-cells : see nand.txt
> +- clocks : phandle to the nand controller clock
> +- clock-names : must contain "nand"

Is there only one clock feeding into the NAND block? Is it actually
called "nand", or does the datasheet not give the input a nme?

> +
> +Optional properties:
> +- samsung,tacls : time for active CLE/ALE to nWE/nOE
> +- samsung,twrph0 : active time for nWE/nOE
> +- samsung,twrph1 : time for release CLE/ALE from nWE/nOE inactive

If these are necessary, what units are these in?

> +- samsung,ignore_unset_ecc : boolean to ignore error when we have
> +                             0xff,0xff,0xff read ECC, on the
> +                             assumption that it is an un-eccd page

s/_/-/ in property names, please.

That said, this name reads like policy rather than a HW description.
Why/when is this necessary to set?

[...]

> +	of_property_read_u32(np, "samsung,tacls",  &pdata->tacls);
> +	of_property_read_u32(np, "samsung,twrph0", &pdata->twrph0);
> +	of_property_read_u32(np, "samsung,twrph1", &pdata->twrph1);

Are all values in the range [0, 0xffffffff] valid for these? If not, it
would be a good idea to sanity-check the values.

> +	if (of_get_property(np, "samsung,ignore_unset_ecc", NULL))
> +		pdata->ignore_unset_ecc = 1;

Use of_property_read_bool();

[...]

> +	for_each_available_child_of_node(np, child) {
> +
> +		sets->name = (char *)child->name;
> +		sets->of_node = child;

Strictly speaking, you should increment the child node refcount here, as
you maintain a reference to it and its name field.

> +		sets->nr_chips = 1;
> +
> +		if (!of_property_match_string(child, "nand-ecc-mode", "none"))
> +			sets->disable_ecc = 1;
> +
> +		if (of_get_property(child, "nand-on-flash-bbt", NULL))
> +			sets->flash_bbt = 1;

Use of_property_read_bool().

Thanks,
Mark.