Re: [PATCH v3 12/12] mfd: cros_ec: Add throttler sub-device

[Brian Norris <briannorris@chromium.org>]

Hi,

On Thu, Jun 14, 2018 at 12:47:12PM -0700, Matthias Kaehlcke wrote:
> Instantiate the CrOS EC throttler if it is enabled in the kernel
> configuration.
> 
> Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
> ---
> Changes in v3:
> - patch added to series
> 
>  drivers/mfd/cros_ec.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/drivers/mfd/cros_ec.c b/drivers/mfd/cros_ec.c
> index 36156a41499c..5f52b6e2c21a 100644
> --- a/drivers/mfd/cros_ec.c
> +++ b/drivers/mfd/cros_ec.c
> @@ -91,6 +91,10 @@ static int cros_ec_sleep_event(struct cros_ec_device *ec_dev, u8 sleep_event)
>  	return cros_ec_cmd_xfer(ec_dev, &buf.msg);
>  }
>  
> +static const struct mfd_cell ec_throttler_cell = {
> +	.name = "cros-ec-throttler",
> +};
> +
>  int cros_ec_register(struct cros_ec_device *ec_dev)
>  {
>  	struct device *dev = ec_dev->dev;
> @@ -153,6 +157,18 @@ int cros_ec_register(struct cros_ec_device *ec_dev)
>  		}
>  	}
>  
> +	if (IS_ENABLED(CONFIG_CROS_EC_THROTTLER)) {
> +		err = mfd_add_devices(ec_dev->dev, PLATFORM_DEVID_AUTO,
> +				      &ec_throttler_cell, 1, NULL, ec_dev->irq,
> +				      NULL);

Most of this similar sub-device registration seems to have moved to
cros_ec_dev.c, in ec_device_probe(). Should this do the same?

And on a similar note: is there a way to determine EC support for this
feature (e.g., EC_FEATURE_*)? Or do we just have to listen for
appropriate throttling events that may never come?

Also, is this very useful on non-DT systems? Does this fail gracefully?

Brian

> +		if (err) {
> +			dev_err(dev,
> +				"Failed to register throttler subdevice %d\n",
> +				err);
> +			return err;
> +		}
> +	}
> +
>  	if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
>  		err = devm_of_platform_populate(dev);
>  		if (err) {
> -- 
> 2.18.0.rc1.242.g61856ae69a-goog
>