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

[David Lechner <dlechner@baylibre.com>]

On 5/18/26 9:59 AM, Sabau, Radu bogdan wrote:
>> -----Original Message-----
>> From: David Lechner <dlechner@baylibre.com>
>> 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?
> 

IIRC, I think it was resolved in a later patch in the series. So
could just be a problem of it not getting added in the right patch.

In general though, yes it would make it easier review if the
direct mode claim was made here.