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Message-ID: <alpine.DEB.2.01.1404150024030.11665@pmeerw.net>
Date: Tue, 15 Apr 2014 00:33:12 +0200 (CEST)
From: Peter Meerwald <pmeerw@...erw.net>
To: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
cc: jic23@...nel.org, linux-iio@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [Patch v5 3/6] IIO: core: Modify scan element type
> 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.
minor comments inline
> ---
> drivers/iio/industrialio-buffer.c | 41 +++++++++++++++++++++++++++++++++------
> include/linux/iio/iio.h | 9 +++++++++
> 2 files changed, 44 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;
so storagebits should be a multiple of 8 and != 0;
we cannot have repeated groups of say 4 bits
> + 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..324ae00 100644
> --- a/include/linux/iio/iio.h
> +++ b/include/linux/iio/iio.h
> @@ -177,6 +177,14 @@ struct iio_event_spec {
> * shift: Shift right by this before masking out
> * realbits.
> * endianness: little or big endian
> + * repeat: No. of times real/storage bits repeats.
I'd rather spell out 'Number'
> + * By default, when repeat is set to 0
> + * repeat value is treated as 1. When
> + * repeat value is 0 or 1, then there is
> + * no change in existing scan element
'no change in existing scan element' -- this makes sense only now
maybe: '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.'
> + * type, in sysfs. When set to more than
no comma before 'in sysfs.'
> + * 1, then the type element in sysfs will
> + * show repeat value.
> * @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 +227,7 @@ struct iio_chan_spec {
> u8 realbits;
> u8 storagebits;
> u8 shift;
> + u8 repeat;
> enum iio_endian endianness;
> } scan_type;
> long info_mask_separate;
>
--
Peter Meerwald
+43-664-2444418 (mobile)
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