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SubjectRe: [PATCHv4 2/5] Input: edt-ft5x06: Add DT support
On Wed, Mar 19, 2014 at 01:09:20PM +0000, Lothar Waßmann wrote:
>
> Signed-off-by: Lothar Waßmann <LW@KARO-electronics.de>
> ---
> .../bindings/input/touchscreen/edt-ft5x06.txt | 41 ++++++
> drivers/input/touchscreen/edt-ft5x06.c | 144 +++++++++++++++-----
> 2 files changed, 154 insertions(+), 31 deletions(-)
> create mode 100644 Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.txt
>
> diff --git a/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.txt b/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.txt
> new file mode 100644
> index 0000000..e5adc76
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.txt
> @@ -0,0 +1,41 @@
> +FocalTech EDT-FT5x06 Polytouch driver
> +=====================================
> +
> +Required properties:
> + - compatible: "edt,edt-ft5x06"
Is the 'x' part of a particular product name, or is this a class of
devices?

It's preferable to have a specific string which another similar variants
can claim compatibility with (while also additionally having a more
specific string), as this makes it possible to handle variants more
specially in future, target workarounds, etc.

> + - reg: I2C slave address of the chip (0x38)
> + - interrupt-parent: a phandle pointing to the interrupt controller
> + serving the interrupt for this chip
> + - interrupts: interrupt specification for this chip

How many? What are they for?

> +
> +Optional properties:
> + - reset-gpios: GPIO specification for the RESET input
> + - wake-gpios: GPIO specification for the WAKE input
> +
> + - pinctrl-names: should be "default"
> + - pinctrl-0: a phandle pointing to the pin settings for the
> + control gpios

These all looks fine.

> +
> + - threshold: allows setting the "click"-threshold in the range
> + from 20 to 80.
> +
> + - gain: allows setting the sensitivity in the range from 0 to
> + 31. Note that lower values indicate higher
> + sensitivity.
> +
> + - offset: allows setting the edge compensation in the range from
> + 0 to 31.

I can see why the sane values for these may differ between boards.

> + - report_rate: allows setting the report rate in the range from 3 to
> + 14.

However, why can the kernel not decide the report rate? This doesn't
sound like something that needs to vary per-board.

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

[...]

> +#define EDT_GET_PROP(name, reg) { \
> + const u32 *prop = of_get_property(np, #name, NULL); \
> + if (prop) \
> + edt_ft5x06_register_write(tsdata, reg, be32_to_cpu(*prop)); \
> +}

Use of_property_read_u32, it'll handle endianness conversion for you.

Use of of_get_property is almost always wrong.

Cheers,
Mark.
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