Re: [PATCH 3/3] iio: imu: adis: add a note better explaining state_lock

Jonathan Cameron
2020-02-21T13:14:53Z

On Fri, 21 Feb 2020 13:49:43 +0200
Alexandru Ardelean <alexandru.ardelean@analog.com> wrote:

> The 'state_lock' mutex was renamed from 'txrx_lock' in a previous patch and
> is intended to be used by ADIS drivers to protect the state of devices
> during consecutive R/W ops.
> The initial patch that introduced this change did not do a good [well, any]
> job at explaining this. This patch adds a comment to the 'state_lock'
> better explaining it's use.

Nice work.

Will pick up in v2.

Thanks,

Jonathan

>
> Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
> ---
> include/linux/iio/imu/adis.h | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/include/linux/iio/imu/adis.h b/include/linux/iio/imu/adis.h
> index 11c915b61ae2..a3110c097fa1 100644
> --- a/include/linux/iio/imu/adis.h
> +++ b/include/linux/iio/imu/adis.h
> @@ -98,6 +98,17 @@ struct adis {
> const struct adis_data *data;
> struct adis_burst *burst;
>
> + /**
> + * The state_lock is meant to be used during operations that require
> + * a sequence of SPI R/W in order to protect the SPI transfer
> + * information (fields 'xfer', 'msg' & 'current_page') between
> + * potential concurrent accesses.
> + * This lock is used by all "adis_{functions}" that have to read/write
> + * registers. These functions also have unlocked variants
> + * (see "__adis_{functions}"), which don't hold this lock.
> + * This allows users of the ADIS library to group SPI R/W into
> + * the drivers, but they also must manage this lock themselves.
> + */
> struct mutex state_lock;
> struct spi_message msg;
> struct spi_transfer *xfer;