Re: [PATCH v5 4/4] iio: adc: ad9467: check for backend capabilities

David Lechner
2026-01-31T20:40:47Z

On 1/30/26 3:17 AM, Tomas Melin wrote:
> Add capability checks for operation with backends that do not necessarily
> support full set of features, but are otherwise compatible with the device.
> This ensures a fully functional device, but with limited capabilities.
>
> Signed-off-by: Tomas Melin <tomas.melin@vaisala.com>
> ---
> drivers/iio/adc/ad9467.c | 69 ++++++++++++++++++++++++++++++------------------
> 1 file changed, 43 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/iio/adc/ad9467.c b/drivers/iio/adc/ad9467.c
> index 59c3fa3bcc9b..d768f7bf2a1c 100644
> --- a/drivers/iio/adc/ad9467.c
> +++ b/drivers/iio/adc/ad9467.c
> @@ -913,7 +913,9 @@ static int __ad9467_update_clock(struct ad9467_state *st, long r_clk)
> return ret;
>
> guard(mutex)(&st->lock);

I saw in the changelog that leaving the guard here was intentional, but I
don't see why.

> - return ad9467_calibrate(st);
> + if (iio_backend_has_caps(st->back, IIO_BACKEND_CAP_CALIBRATION))
> + return ad9467_calibrate(st);
> + return 0;
> }
>

...

> static int ad9467_write_raw(struct iio_dev *indio_dev,
> @@ -1119,12 +1121,15 @@ static ssize_t ad9467_chan_test_mode_read(struct file *file,
> len = scnprintf(buf, sizeof(buf), "Running \"%s\" Test:\n\t",
> ad9467_test_modes[chan->mode]);
>
> - ret = iio_backend_debugfs_print_chan_status(st->back, chan->idx,
> - buf + len,
> - sizeof(buf) - len);
> - if (ret < 0)
> - return ret;
> - len += ret;
> + if (iio_backend_has_caps(st->back, IIO_BACKEND_CAP_CALIBRATION)) {
> + ret = iio_backend_debugfs_print_chan_status(st->back,
> + chan->idx,
> + buf + len,
> + sizeof(buf) - len);
> + if (ret < 0)
> + return ret;
> + len += ret;
> + }
> } else if (chan->mode == AN877_ADC_TESTMODE_OFF) {
> len = scnprintf(buf, sizeof(buf), "No test Running...\n");
> } else {
> @@ -1188,16 +1193,19 @@ static ssize_t ad9467_chan_test_mode_write(struct file *file,
> return ret;
>
> /* some patterns have a backend matching monitoring block */
> - if (mode == AN877_ADC_TESTMODE_PN9_SEQ) {
> - ret = ad9467_backend_testmode_on(st, chan->idx,
> + if (iio_backend_has_caps(st->back,
> + IIO_BACKEND_CAP_CALIBRATION)) {
> + if (mode == AN877_ADC_TESTMODE_PN9_SEQ) {
> + ret = ad9467_backend_testmode_on(st, chan->idx,
> IIO_BACKEND_ADI_PRBS_9A);
> - if (ret)
> - return ret;
> - } else if (mode == AN877_ADC_TESTMODE_PN23_SEQ) {
> - ret = ad9467_backend_testmode_on(st, chan->idx,
> + if (ret)
> + return ret;
> + } else if (mode == AN877_ADC_TESTMODE_PN23_SEQ) {
> + ret = ad9467_backend_testmode_on(st, chan->idx,
> IIO_BACKEND_ADI_PRBS_23A);
> - if (ret)
> - return ret;
> + if (ret)
> + return ret;
> + }
> }
> }
>
> @@ -1263,8 +1271,10 @@ static void ad9467_debugfs_init(struct iio_dev *indio_dev)
> if (!st->chan_test)
> return;
>
> - debugfs_create_file("calibration_table_dump", 0400, d, st,
> - &ad9467_calib_table_fops);
> + if (iio_backend_has_caps(st->back, IIO_BACKEND_CAP_CALIBRATION)) {
> + debugfs_create_file("calibration_table_dump", 0400, d, st,
> + &ad9467_calib_table_fops);
> + }
>
> for (chan = 0; chan < st->info->num_channels; chan++) {
> snprintf(attr_name, sizeof(attr_name), "in_voltage%u_test_mode",

Do we actually need to change these test mode/debugfs functions since
debugfs_create_file() is only callded if IIO_BACKEND_CAP_CALIBRATION
already?