linux-kernel - Re: [PATCH 3/3] iio: imu: adis: add a note better explaining state

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Date:   Fri, 21 Feb 2020 13:14:46 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Alexandru Ardelean <alexandru.ardelean@...log.com>
Cc:     <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/3] iio: imu: adis: add a note better explaining
 state_lock

On Fri, 21 Feb 2020 13:49:43 +0200
Alexandru Ardelean <alexandru.ardelean@...log.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@...log.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;