Re: [PATCH v2 2/7] iio: adc: max1027: Make it optional to use interrupts

Jonathan Cameron
2019-10-06T10:18:45Z

On Thu, 3 Oct 2019 19:33:56 +0200
Miquel Raynal <miquel.raynal@bootlin.com> wrote:

> The chip has a 'start conversion' and a 'end of conversion' pair of
> pins. They can be used but this is absolutely not mandatory as regular
> polling of the value is totally fine with the current internal
> clocking setup. Turn the interrupts optional and do not error out if
> they are not inquired in the device tree. This has the effect to
> prevent triggered buffers use though.
>
> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

Hmm. I haven't looked a this in a great deal of depth but if we support
single channel reads it should be possible to allow the use of a
trigger from elsewhere. Looks like a fair bit of new code would be needed
to support that though. So perhaps this is a good first step.

It's a bit annoying that the hardware doesn't provide a EOC bit
anywhere in the registers. That would have allowed us to be a bit
cleverer.

Anyhow, this looks fine to me.

Thanks,

Jonathan

> ---
> drivers/iio/adc/max1027.c | 57 +++++++++++++++++++++------------------
> 1 file changed, 31 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/iio/adc/max1027.c b/drivers/iio/adc/max1027.c
> index 6cdfe9ef73fc..823223b77a70 100644
> --- a/drivers/iio/adc/max1027.c
> +++ b/drivers/iio/adc/max1027.c
> @@ -430,35 +430,40 @@ static int max1027_probe(struct spi_device *spi)
> return -ENOMEM;
> }
>
> - ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev,
> - &iio_pollfunc_store_time,
> - &max1027_trigger_handler, NULL);
> - if (ret < 0) {
> - dev_err(&indio_dev->dev, "Failed to setup buffer\n");
> - return ret;
> - }

> + if (spi->irq) {
> + ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev,
> + &iio_pollfunc_store_time,
> + &max1027_trigger_handler,
> + NULL);
> + if (ret < 0) {
> + dev_err(&indio_dev->dev, "Failed to setup buffer\n");
> + return ret;
> + }
>
> - st->trig = devm_iio_trigger_alloc(&spi->dev, "%s-trigger",
> - indio_dev->name);
> - if (st->trig == NULL) {
> - ret = -ENOMEM;
> - dev_err(&indio_dev->dev, "Failed to allocate iio trigger\n");
> - return ret;
> - }
> + st->trig = devm_iio_trigger_alloc(&spi->dev, "%s-trigger",
> + indio_dev->name);
> + if (st->trig == NULL) {
> + ret = -ENOMEM;
> + dev_err(&indio_dev->dev,
> + "Failed to allocate iio trigger\n");
> + return ret;
> + }
>
> - st->trig->ops = &max1027_trigger_ops;
> - st->trig->dev.parent = &spi->dev;
> - iio_trigger_set_drvdata(st->trig, indio_dev);
> - iio_trigger_register(st->trig);
> + st->trig->ops = &max1027_trigger_ops;
> + st->trig->dev.parent = &spi->dev;
> + iio_trigger_set_drvdata(st->trig, indio_dev);
> + iio_trigger_register(st->trig);
>
> - ret = devm_request_threaded_irq(&spi->dev, spi->irq,
> - iio_trigger_generic_data_rdy_poll,
> - NULL,
> - IRQF_TRIGGER_FALLING,
> - spi->dev.driver->name, st->trig);
> - if (ret < 0) {
> - dev_err(&indio_dev->dev, "Failed to allocate IRQ.\n");
> - return ret;
> + ret = devm_request_threaded_irq(&spi->dev, spi->irq,
> + iio_trigger_generic_data_rdy_poll,
> + NULL,
> + IRQF_TRIGGER_FALLING,
> + spi->dev.driver->name,
> + st->trig);
> + if (ret < 0) {
> + dev_err(&indio_dev->dev, "Failed to allocate IRQ.\n");
> + return ret;
> + }
> }
>
> /* Disable averaging */