Re: [RFC PATCH] WIP: i2c: rcar: add HostNotify support

Wolfram Sang
2020-07-01T13:21:49Z

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> > I got another idea. What about a boolean binding "smbus"?
...
>
> I much prefer this solution than the usage of the smbus_alert irq value
> (in case of the i2c-stm32f7). In that case, I'd only set smbus boolean
> to enable both SMBus Host-Notify & SMBus Alert.

Correct.

> In case of a device having a dedicated irq for SMBus Alert, smbus_alert
> irq binding would still be needed.

Yes, that was my idea. Let's use "smbus".

> Just my 2 cents about another aspect regarding SMBus Alert, since alert
> is coming from another pin and not the usual SCL / SCK, when SMBus Alert
> has to be used, there is a very good chance to have a pinctrl entry which
> is different from not using SMBus Alert.
> Indeed, even if we need SMBus, but don't need SMBus Alert, the SMBus Alert
> input pin might be used for something else.
> But this of course doesn't prevent to use the smbus boolean binding.

I am not sure if I fully get this point. Either we have a dedicated line
(your case) or we need to use a GPIO as an interrupt line (my case). So,
either this is configured correctly in DT and added as a "smbus_alert"
irq. Or this irq is missing and then the driver will ignore SMBusAlert
and the GPIO can be freely used/muxed. Or?