Re: [PATCH v2 2/3] iio: adc: xilinx-ams: use device_* to iterate over device child nodes

Jonathan Cameron
2024-08-10T10:39:02Z

On Thu, 08 Aug 2024 17:12:38 +0200
Javier Carrasco <javier.carrasco.cruz@gmail.com> wrote:

> Use `device_for_each_child_node_scoped()` in `ams_parse_firmware()`
> to explicitly state device child node access, and simplify the child
> node handling as it is not required outside the loop.
>
> Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>

One follow up question for those familiar with the driver.
Why do we check if the main device is available?
if (fwnode_device_is_available(fwnode)) {
ret = ams_init_module(indio_dev, fwnode, ams_channels);
if (ret < 0)
return ret;

num_channels += ret;
}

How is the platform device driver probed if it's not available?

Jonathan

> ---
> drivers/iio/adc/xilinx-ams.c | 15 +++++----------
> 1 file changed, 5 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/iio/adc/xilinx-ams.c b/drivers/iio/adc/xilinx-ams.c
> index f051358d6b50..ebc583b07e0c 100644
> --- a/drivers/iio/adc/xilinx-ams.c
> +++ b/drivers/iio/adc/xilinx-ams.c
> @@ -1275,7 +1275,6 @@ static int ams_parse_firmware(struct iio_dev *indio_dev)
> struct ams *ams = iio_priv(indio_dev);
> struct iio_chan_spec *ams_channels, *dev_channels;
> struct device *dev = indio_dev->dev.parent;
> - struct fwnode_handle *child = NULL;
> struct fwnode_handle *fwnode = dev_fwnode(dev);
> size_t ams_size;
> int ret, ch_cnt = 0, i, rising_off, falling_off;
> @@ -1297,16 +1296,12 @@ static int ams_parse_firmware(struct iio_dev *indio_dev)
> num_channels += ret;
> }
>
> - fwnode_for_each_child_node(fwnode, child) {
> - if (fwnode_device_is_available(child)) {
> - ret = ams_init_module(indio_dev, child, ams_channels + num_channels);
> - if (ret < 0) {
> - fwnode_handle_put(child);
> - return ret;
> - }
> + device_for_each_child_node_scoped(dev, child) {
> + ret = ams_init_module(indio_dev, child, ams_channels + num_channels);
> + if (ret < 0)
> + return ret;
>
> - num_channels += ret;
> - }
> + num_channels += ret;
> }
>
> for (i = 0; i < num_channels; i++) {
>