Re: [PATCH RFC v2 1/2] Documentation: dt: net: add ath9k wireless device binding

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

On Thu, Jun 23, 2016 at 07:45:35PM +0200, Martin Blumenstingl wrote:
> Add documentation how devicetree can be used to configure ath9k based
> devices.
> 
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
> ---
> changes in v1 -> v2:
> - use vendor prefix "qca" instead of "ath"
> - extend the example so it includes the "compatible" property
> 
>  .../devicetree/bindings/net/wireless/qca,ath9k.txt | 41 ++++++++++++++++++++++
>  1 file changed, 41 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/net/wireless/qca,ath9k.txt
> 
> diff --git a/Documentation/devicetree/bindings/net/wireless/qca,ath9k.txt b/Documentation/devicetree/bindings/net/wireless/qca,ath9k.txt
> new file mode 100644
> index 0000000..bb78f68
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/net/wireless/qca,ath9k.txt
> @@ -0,0 +1,41 @@
> +* Qualcomm Atheros ath9k wireless devices
> +
> +This node provides properties for configuring the ath9k wireless device. The
> +node is expected to be specified as a child node of the PCI controller to
> +which the wireless chip is connected.
> +
> +Required properties:
> +- compatible: Should be "qca,ath9k"
> +
> +Optional properties:
> +- reg: Address and length of the register set for the device.
> +- qca,gpio-mask: The GPIO mask
> +- qca,gpio-val: The GPIO value
> +- qca,led-pin: The GPIO number to which the LED is connected
> +- qca,led-active-high: The LED is active when the GPIO is HIGH
> +- qca,clk-25mhz: Defines that at 25MHz clock is used

I must assume these apply to internal GPIOs, LEDs and clocks, so I'm
somewhat surprised any description is necessary.

How variable are these in practice?

> +- qca,eeprom-name: The name of the file which contains the EEPROM data (which
> +			will be loaded via request_firmware)

The binding shouldn't know anything about the host filesystem,
request_firmware, etc. So the description is a best a little off.

What happens when a new FW comes out? I shouldn't have to update my DT
to cater for that.

Please find a better way to identify relevant FW. What exactly affects
which FW can be used, or would ideally be used? Are different FWs
required for the same HW in some contexts?

Can we not figure out the relevant FW names in the driver based on some
identification mechanism (e.g. a more thoroughly defined set of
compatible strings)?

> +- qca,check-eeprom-endianness: Allow checking the EEPROM endianness and
> +				swapping of the EEPROM data if required

CAn we not simply always do this?

> +- qca,disable-2ghz: Disables the 2.4GHz band, even if enabled in the EEPROM
> +- qca,disable-5ghz: Disables the 5GHz band, even if enabled in the EEPROM

When/why would these be necessary?

Thanks,
Mark.