Hello Jonathan,
Some explanations from my side.
>> @@ -437,6 +467,130 @@ static int adis16475_set_filter(struct adis16475 *st, const u32 filter)
>> return 0;
>> }
>>
>> +static ssize_t adis16475_get_fifo_enabled(struct device *dev,
>> + struct device_attribute *attr,
>> + char *buf)
>> +{
>> + struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>> + struct adis16475 *st = iio_priv(indio_dev);
>> + int ret;
>> + u16 val;
>> +
>> + ret = adis_read_reg_16(&st->adis, ADIS16475_REG_FIFO_CTRL, &val);
>> + if (ret)
>> + return ret;
>> + val = FIELD_GET(ADIS16475_FIFO_EN_MASK, val);
>> +
>> + return sysfs_emit(buf, "%d\n", val);
> As below, might as well put the FIELD_GET() in the sysfs_emit rather than
> writing the local parameter.
In all instances where I did, I did it to avoid casting. v2 inlines the values and
the cast is needed to avoid compilation errors.
>
>> + if (adis->data->burst_max_len)
>> + burst_max_length = adis->data->burst_max_len;
>> + else
>> + burst_max_length = burst_length;
>> +
>> + tx = adis->buffer + burst_max_length;
>> + tx[0] = ADIS_READ_REG(burst_req);
>> +
>> + if (burst_req)
> If !burst_req does the rest of this do anything at all?
> If so flip the logic as
> if (!burst_req)
> return adis16475_push_single_sample(pf);
>
> the rest...
> return spi_sync(adis->spi, &adis->msg);
The update is needed even if burst_req is false. The adis message has to be updated
based on the burst request value, which is then used either in
adis16475_push_single_sample or in spi_sync call.
>
>
>> + return spi_sync(adis->spi, &adis->msg);
>> +
>> + return adis16475_push_single_sample(pf);
>> +}
>> +
>> +/*
>> + * This handler is meant to be used for devices which support burst readings
>> + * from FIFO (namely devices from adis1657x family).
>> + * In order to pop the FIFO the 0x68 0x00 FIFO pop burst request has to be sent.
>> + * If the previous device command was not a FIFO pop burst request, the FIFO pop
>> + * burst request will simply pop the FIFO without returning valid data.
>> + * For the nth consecutive burst request, the
>> + * device will send the data popped with the (n-1)th consecutive burst request.
>> + * In order to read the data which was popped previously, without popping the FIFO,
>> + * the 0x00 0x00 burst request has to be sent.
>> + * If after a 0x68 0x00 FIFO pop burst request, there is any other device access
>> + * different from a 0x68 0x00 or a 0x00 0x00 burst request, the FIFO data popped
>> + * previously will be lost.
>> + */
>> +static irqreturn_t adis16475_trigger_handler_with_fifo(int irq, void *p)
>> {
>> struct iio_poll_func *pf = p;
>> struct iio_dev *indio_dev = pf->indio_dev;
>> + struct adis16475 *st = iio_priv(indio_dev);
>> + struct adis *adis = &st->adis;
>> + int ret;
>> + u16 fifo_cnt, i;
>>
>> - adis16475_push_single_sample(pf);
>> + adis_dev_lock(&st->adis);
>> +
>> + ret = __adis_read_reg_16(adis, ADIS16475_REG_FIFO_CNT, &fifo_cnt);
>> + if (ret || fifo_cnt < 2)
>> + goto unlock;
> I would break these conditions and add a comment on why fifo_cnt < 2 is
> a reason to just return 0;
Updated this in v2, and actually fifo_cnt can also be 1 so the code simply
verifies if !fifo_cnt.
>
>> +
>> + if (fifo_cnt > st->fifo_watermark)
>> + fifo_cnt = st->fifo_watermark;
> fifo_cnt = min(fifo_cnt, st->fifo_watermark);
>
> This confuses me though as normally overreading after a fifo watermark is
> both safe and the right thing to do (as reduces chance of overflow etc).
> If we need to clamp to the watermark for some reason, add a comment.
Removed this in v2.
>>
>> ret = __adis_write_reg_16(&st->adis,
>> ADIS16475_REG_UP_SCALE,
>> @@ -1467,7 +1888,23 @@ static int adis16475_config_irq_pin(struct adis16475 *st)
>> */
>> usleep_range(250, 260);
>>
>> - return 0;
>> + /*
>> + * If the device has FIFO support, configure the watermark polarity
>> + * pin as well.
> The pin is for polarity or the polarity is for the watermark signalling on that
> pin? I'm not seeing a datasheet yet for these parts so I couldn't check.
The device has a watermark pin, which can be used as a trigger source.
In this case we set the polarity for the watermark pin.
>
>> + */
>> + if (st->info->flags & ADIS16475_HAS_FIFO) {
>> + val = ADIS16475_WM_POL(polarity);
>> + ret = adis_update_bits(&st->adis, ADIS16475_REG_FIFO_CTRL,
>> + ADIS16475_WM_POL_MASK, val);
>> + if (ret)
>> + return ret;
>> +
>> + /* Enable watermark interrupt pin. */
>> + val = ADIS16475_WM_EN(1);
>> + ret = adis_update_bits(&st->adis, ADIS16475_REG_FIFO_CTRL, ADIS16475_WM_EN_MASK, val);
Best Regards,
Ramona
