> -----Original Message-----
> From: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
> Sent: Wednesday, August 18, 2021 1:12 PM
> To: Jonathan Cameron <jic23@xxxxxxxxxx>; Lars-Peter Clausen
> <lars@xxxxxxxxxx>
> Cc: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxx>; linux-
> iio@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Miquel Raynal
> <miquel.raynal@xxxxxxxxxxx>
> Subject: [PATCH 12/16] iio: adc: max1027: Introduce an end of
> conversion helper
>
> [External]
>
> For now this helper only waits for the maximum duration of a
> conversion,
> but it will soon be improved to properly handle the end of conversion
> interrupt.
>
> Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
> ---
> drivers/iio/adc/max1027.c | 23 +++++++++++++++++++++--
> 1 file changed, 21 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iio/adc/max1027.c b/drivers/iio/adc/max1027.c
> index afc3ce69f7ea..2d6485591761 100644
> --- a/drivers/iio/adc/max1027.c
> +++ b/drivers/iio/adc/max1027.c
> @@ -60,6 +60,9 @@
> #define MAX1027_NAVG_32 (0x03 << 2)
> #define MAX1027_AVG_EN BIT(4)
>
> +/* Device can achieve 300ksps so we assume a 3.33us conversion
> delay */
> +#define MAX1027_CONVERSION_UDELAY 4
> +
> enum max1027_id {
> max1027,
> max1029,
> @@ -236,6 +239,20 @@ struct max1027_state {
> u8 reg ____cacheline_aligned;
> };
>
> +static DECLARE_WAIT_QUEUE_HEAD(max1027_queue);
> +
> +static int max1027_wait_eoc(struct iio_dev *indio_dev)
> +{
> + unsigned int conversion_time =
> MAX1027_CONVERSION_UDELAY;
> +
> + if (indio_dev->active_scan_mask)
> + conversion_time *= hweight32(*indio_dev-
> >active_scan_mask);
> +
> + usleep_range(conversion_time, conversion_time * 2);
> +
> + return 0;
> +}
> +
> /* Scan from 0 to the highest requested channel */
> static int max1027_configure_chans_to_scan(struct iio_dev
> *indio_dev)
> {
> @@ -310,9 +327,11 @@ static int max1027_read_single_value(struct
> iio_dev *indio_dev,
> /*
> * For an unknown reason, when we use the mode "10" (write
> * conversion register), the interrupt doesn't occur every time.
> - * So we just wait 1 ms.
> + * So we just wait the maximum conversion time and deliver
> the value.
> */
> - mdelay(1);
> + ret = max1027_wait_eoc(indio_dev);
> + if (ret)
> + return ret;
I'm a bit confused here... Why are we looking at the active_scan_mask?
Aren't we preventing this for running concurrently with buffering?
- Nuno Sá
>
> /* Read result */
> ret = spi_read(st->spi, st->buffer, (chan->type == IIO_TEMP) ?
> 4 : 2);
> --
> 2.27.0
