Re: [PATCH v2 3/5] dt-bindings: Document common property for daisy-chained devices

[Rob Herring <robh@xxxxxxxxxx>]

On Thu, Oct 12, 2017 at 12:40:10PM +0200, Lukas Wunner wrote:
> Many serially-attached GPIO and IIO devices are daisy-chainable.
> 
>     Examples for GPIO devices are Maxim MAX3191x and TI SN65HVS88x:
>     https://datasheets.maximintegrated.com/en/ds/MAX31913.pdf
>     http://www.ti.com/lit/ds/symlink/sn65hvs880.pdf
> 
>     Examples for IIO devices are TI DAC128S085 and TI DAC161S055:
>     http://www.ti.com/lit/ds/symlink/dac128s085.pdf
>     http://www.ti.com/lit/ds/symlink/dac161s055.pdf
> 
> We already have drivers for daisy-chainable devices in the tree but
> their devicetree bindings are somewhat inconsistent and ill-named:
> 
>     The gpio-74x164.c driver uses "registers-number" to convey the
>     number of devices in the daisy-chain.  (Sans vendor prefix,
>     multiple vendors sell compatible versions of this chip.)
> 
>     The gpio-pisosr.c driver takes a different approach and calculates
>     the number of devices in the daisy-chain by dividing the common
>     "ngpios" property (Documentation/devicetree/bindings/gpio/gpio.txt)
>     by 8 (which assumes that each chip has 8 inputs).
> 
> Let's standardize on a common "#daisy-chained-devices" property.
> That name was chosen because it's the term most frequently used in
> datasheets.  (A less frequently used synonym is "cascaded devices".)
> 
> Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
> ---
> Changes v1 -> v2:
> 
> - Newly inserted patch.
> 
>  .../devicetree/bindings/common-properties.txt      | 26 ++++++++++++++++++++++
>  1 file changed, 26 insertions(+)

Acked-by: Rob Herring <robh@xxxxxxxxxx>

--
To unsubscribe from this list: send the line "unsubscribe linux-gpio" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html