RE: [PATCH v11 2/6] iio: adc: ad4691: add initial driver for AD4691 family

[Sabau, Radu bogdan]

> -----Original Message-----
> From: David Lechner <dlechner@xxxxxxxxxxxx>
> Sent: Saturday, May 16, 2026 8:11 PM

...

> > +static int ad4691_reg_read(void *context, unsigned int reg, unsigned int
> *val)
> > +{
> > +	struct spi_device *spi = context;
> > +	u8 tx[2], rx[4];
> > +	int ret;
> > +
> > +	/* Set bit 15 to mark the operation as READ. */
> 
> Can't we just set read_flag_mask in the regmap config?
> 

As far as I can tell read_flag_mask is applied by the standard SPI regmap bus
backend, which constructs and sends the address byte itself before reading
the response. When using devm_regmap_init() with custom reg_read/reg_write
callbacks, the regmap core calls those callbacks directly with the raw register
address - it never touches read_flag_mask.

> > +	put_unaligned_be16(0x8000 | reg, tx);
> > +
> > +	switch (reg) {
> > +	case 0 ... AD4691_OSC_FREQ_REG:
> > +	case AD4691_SPARE_CONTROL ... AD4691_ACC_MASK_REG - 1:

...

> > +static int ad4691_write_raw(struct iio_dev *indio_dev,
> > +			    struct iio_chan_spec const *chan,
> > +			    int val, int val2, long mask)
> > +{
> > +	switch (mask) {
> > +	case IIO_CHAN_INFO_SAMP_FREQ:
> 
> Should we aquire direct mode so that we can't change the rate during
> buffered read?
> 

It is in set_sampling_freq already. Do you think it would make more sense
to move it here in order to help readability?