Re: [PATCH v2] DocBook: Add initial documentation for IIO

[Daniel Baluta]

<snip>

>> +      converters (DACs), that functionality is also supported.
>
>
> I wouldn't necessarily treat DACs and ADCs differently here. Maybe something
> like:
>
>   The main purpose of the Industrial I/O subsystem (IIO) is to provide
>   support for devices that in some sense perform either analog-to-digital
>   conversion (ADC) or digital-to-analog conversion (DAC) or both.

Ok. Fixed.

>> +    <para> In order to be useful, a buffer needs to have an associated
>> +      trigger. Future chapters will add details about triggers and how
>> +      drivers use triggers to start data capture, moving samples from
>> device
>> +      registers to buffer storage and then upward to user space
>> applications.
>
>
> Buffers don't have to have a trigger, only triggered buffers need them.
> Although admittedly most buffers will be triggered buffers. I think it's
> better to talk about buffers in general first and then discuss the different
> types of buffers and when to use them. In this context it should be
> mentioned that a triggered buffer needs a trigger to function.

I removed this paragraph for the moment, will try to add more info about
buffer here with a follow up patch.

<snip>

>> +        </itemizedlist>
>
>
> The scan type gained a repeat field a while ago.

Nice catch. Fixed. Also will send a patch to fix the ABI entry description.

<snip>

>> +    Here <emphasis> scan_index </emphasis> is used for ordering data
>> samples
>> +    (scans) when read from buffer.
>
>
> A bit more:
>
>   scan_index defines the relative order in which the enabled channels
>   are placed inside the buffer, a channel with a lower scan_index will be
>   placed before a channel with a higher index. Each channels needs to have
>   a unique scan_index.
>
>   It is important to realize that the scan_index does not define the
>   absolution position in the buffer. E.g. a channel with the scan_index = 3
>   will not be at offset 3 bytes or 3 words, but rather will be placed in
>   the buffer after any channel with a scan_index lower than 3 and before
>   any channel with a scan_index larger than 3.
>
>   Furthermore the scan indices do not have to be consecutive. E.g. A
>   channel spec array that defines 3 channels with the indices 1, 2 and 3 is
>   just as valid as a channel spec that uses the indices 100, 200, 300. The
>   relative order of the channels will be the same.
>
>   Setting scan_index to -1 can be used to indicate that the specific
>   channel does not support buffered capture. In this case no entries will
>   be created for the channel in the scan_elements directory.

Nice. I've included this in the documentation.

Thanks a lot Lars for your review.

Daniel.
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