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SubjectRe: [PATCH] DocBook: Add initial documentation for IIO
Date
Daniel Baluta writes: 

> On Thu, Jul 16, 2015 at 10:31 PM, Jonathan Cameron <jic23@kernel.org> wrote:
>
> Thanks for your review Jonathan! I will try to address your
> comments in v2.
>
>
>>>+ The main purpose of the Industrial I/O subsystem (IIO) is to
>>>provide
>>>+ support for devices that in some sense are analog to digital
>>>converts
>>>+ (ADCs). As many actual devices combine some ADCs with digital to
>>>analog
>>>+ converters (DACs), that functionality is also supported.
>>
>> I wonder if we now want to treat DACs at the same level in the docs as ADCs. Right
>> now our support is simpler but there are patches adding full buffered support to output devices as well (Lars?)
>
> I have very few experience with DACs IIO drivers :) but I assume that
> the basic part
> is the same (e.g. set .output = 1) then triggers are independent of
> device type :).
>
> Anyhow, the above line only says that IIO also supports DACs and then
> all the examples
> are for ADCs :). Perhaps I can make the examples more clear.
>
> <snip>
>
>>
>>>+ Usually these sensors are connected via SPI or I2C.
>> Maybe add something about SOC integrated parts as well?
>
> Like sensors hubs? We can add this later.
Not so much sensor hubs (though could mention those as well).
A lot of our ADCs are integrated in various (typically arm) SOCs.
These then provide services to other users (battery etc) as needed.
>
>>>+ <para>
>>>+ The Industrial I/O core offers a way for continuous data capture
>>>+ based on a trigger source. Multiple data channels can be read at
>>>once
>>>+ from <filename>/dev/iio:deviceX</filename> character device node,
>>>+ thus reducing the CPU load.
>>>+ </para>
>> Why reduced load? Also perhaps mention pseudo scans? (Sort of all at the same time)
>
> Because, the alternative would be to use "polling" on sysfs data
> attributes. This means:
> * 3 userspace read()'s instead of 1.
> * 3 kernel separate register reads instead 1 bulk read.
>
> Perhaps I can make this clearer. :)
Also make the point that the interface is binary and scaling / offsets
left to userspace. Just wants some explanation I think!
>
> <snip>
>
>> Sorry for messy review. Ignoring my daughter down the park:)
>>
>> Anyhow, a great basis to build on. I like the example driven approach.
>> Might have missed it but perhaps cross refer to the dummy driver?
>
> Thanks again for your time Jonathan! We are really happy with your
> per weekend review sessions, so you would better stay away from
> your phone while in the park :D.
*laughs*. My daughter's 9. She doesn't really need pushing on the swings
any more. Just keeps coming over to see what I'm doing :)

Busy with Ballet shows this weekend and holiday next so got to fit
the odd bit in mid week at the moment :)
>
> thanks,
> Daniel.


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