Re: [Patch v6 3/6] IIO: core: Modify scan element type

[Jonathan Cameron <jic23@kernel.org>]

On 15/04/14 19:21, Srinivas Pandruvada wrote:
> The current scan element type uses the following format:
>    [be|le]:[s|u]bits/storagebits[>>shift].
> To specify multiple elements in this type, added a repeat value.
> So new format is:
>    [be|le]:[s|u]bits/storagebits{X[repeat]}[>>shift].
> Here X is specifying how may times, real/storage bits are repeating.
>
> When X is value is 0 or 1, then repeat value is not used in the format,
> and it will be same as existing format.
>
> Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Hi Srinivas,

I'm afraid I've been rather useless in my reviewing of earlier versions of this.
What I originally meant to suggest was that we'd have descriptions along the lines
of
u12/16{X4}>>2 (or u12/16X4>>2 without the brackets) rather than u12/16{4repeat}>>2

Now obviously you've gone a long way with this approach so I guess perhaps people
actually like the word repeat in there?

Sorry again that I didn't pick up on this in any of the last 4 versions you have posted.
Sometimes the eye sees what it expects to rather than what is there!

I don't particularly mind the version using the word 'repeat' if others like, it simply
isn't what I thought we had here!

(the rest of this series are fine now btw)

J
> ---
>   drivers/iio/industrialio-buffer.c | 41 +++++++++++++++++++++++++++++++++------
>   include/linux/iio/iio.h           |  7 +++++++
>   2 files changed, 42 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
> index e108f2a..aa90c68 100644
> --- a/drivers/iio/industrialio-buffer.c
> +++ b/drivers/iio/industrialio-buffer.c
> @@ -150,7 +150,16 @@ static ssize_t iio_show_fixed_type(struct device *dev,
>   		type = IIO_BE;
>   #endif
>   	}
> -	return sprintf(buf, "%s:%c%d/%d>>%u\n",
> +	if (this_attr->c->scan_type.repeat > 1)
> +		return sprintf(buf, "%s:%c%d/%d{%d[repeat]}>>%u\n",
> +		       iio_endian_prefix[type],
> +		       this_attr->c->scan_type.sign,
> +		       this_attr->c->scan_type.realbits,
> +		       this_attr->c->scan_type.storagebits,
> +		       this_attr->c->scan_type.repeat,
> +		       this_attr->c->scan_type.shift);
> +		else
> +			return sprintf(buf, "%s:%c%d/%d>>%u\n",
>   		       iio_endian_prefix[type],
>   		       this_attr->c->scan_type.sign,
>   		       this_attr->c->scan_type.realbits,
> @@ -474,14 +483,22 @@ static int iio_compute_scan_bytes(struct iio_dev *indio_dev,
>   	for_each_set_bit(i, mask,
>   			 indio_dev->masklength) {
>   		ch = iio_find_channel_from_si(indio_dev, i);
> -		length = ch->scan_type.storagebits / 8;
> +		if (ch->scan_type.repeat > 1)
> +			length = ch->scan_type.storagebits / 8 *
> +				ch->scan_type.repeat;
> +		else
> +			length = ch->scan_type.storagebits / 8;
>   		bytes = ALIGN(bytes, length);
>   		bytes += length;
>   	}
>   	if (timestamp) {
>   		ch = iio_find_channel_from_si(indio_dev,
>   					      indio_dev->scan_index_timestamp);
> -		length = ch->scan_type.storagebits / 8;
> +		if (ch->scan_type.repeat > 1)
> +			length = ch->scan_type.storagebits / 8 *
> +				ch->scan_type.repeat;
> +		else
> +			length = ch->scan_type.storagebits / 8;
>   		bytes = ALIGN(bytes, length);
>   		bytes += length;
>   	}
> @@ -957,7 +974,11 @@ static int iio_buffer_update_demux(struct iio_dev *indio_dev,
>   					       indio_dev->masklength,
>   					       in_ind + 1);
>   			ch = iio_find_channel_from_si(indio_dev, in_ind);
> -			length = ch->scan_type.storagebits/8;
> +			if (ch->scan_type.repeat > 1)
> +				length = ch->scan_type.storagebits / 8 *
> +					ch->scan_type.repeat;
> +			else
> +				length = ch->scan_type.storagebits / 8;
>   			/* Make sure we are aligned */
>   			in_loc += length;
>   			if (in_loc % length)
> @@ -969,7 +990,11 @@ static int iio_buffer_update_demux(struct iio_dev *indio_dev,
>   			goto error_clear_mux_table;
>   		}
>   		ch = iio_find_channel_from_si(indio_dev, in_ind);
> -		length = ch->scan_type.storagebits/8;
> +		if (ch->scan_type.repeat > 1)
> +			length = ch->scan_type.storagebits / 8 *
> +				ch->scan_type.repeat;
> +		else
> +			length = ch->scan_type.storagebits / 8;
>   		if (out_loc % length)
>   			out_loc += length - out_loc % length;
>   		if (in_loc % length)
> @@ -990,7 +1015,11 @@ static int iio_buffer_update_demux(struct iio_dev *indio_dev,
>   		}
>   		ch = iio_find_channel_from_si(indio_dev,
>   			indio_dev->scan_index_timestamp);
> -		length = ch->scan_type.storagebits/8;
> +		if (ch->scan_type.repeat > 1)
> +			length = ch->scan_type.storagebits / 8 *
> +				ch->scan_type.repeat;
> +		else
> +			length = ch->scan_type.storagebits / 8;
>   		if (out_loc % length)
>   			out_loc += length - out_loc % length;
>   		if (in_loc % length)
> diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
> index 5629c92..ccde917 100644
> --- a/include/linux/iio/iio.h
> +++ b/include/linux/iio/iio.h
> @@ -177,6 +177,12 @@ struct iio_event_spec {
>    *			shift:		Shift right by this before masking out
>    *					realbits.
>    *			endianness:	little or big endian
> + *			repeat:		Number of times real/storage bits
> + *					repeats. When the repeat element is
> + *					more than 1, then the type element in
> + *					sysfs will show a repeat value.
> + *					Otherwise, the number of repetitions is
> + *					omitted.
>    * @info_mask_separate: What information is to be exported that is specific to
>    *			this channel.
>    * @info_mask_shared_by_type: What information is to be exported that is shared
> @@ -219,6 +225,7 @@ struct iio_chan_spec {
>   		u8	realbits;
>   		u8	storagebits;
>   		u8	shift;
> +		u8	repeat;
>   		enum iio_endian endianness;
>   	} scan_type;
>   	long			info_mask_separate;
>