Re: [PATCH] iio: industrialio-core: look for aliases to request device index

[Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>]

On 28/02/2024 08:31, Dominique Martinet wrote:
> Krzysztof Kozlowski wrote on Wed, Feb 28, 2024 at 08:16:03AM +0100:
>> On 28/02/2024 06:12, Dominique Martinet wrote:
>>> From: Syunya Ohshio <syunya.ohshio@atmark-techno.com>
>>>
>>> When using dtb overlays it can be difficult to predict which iio device
>>> will get assigned what index, and there is no easy way to create
>>> symlinks for /sys nodes through udev so to simplify userspace code make
>>> it possible to request fixed indices for iio devices in device tree.
>>
>> Please use subject prefixes matching the subsystem. You can get them for
>> example with `git log --oneline -- DIRECTORY_OR_FILE` on the directory
>> your patch is touching.
> 
> Sorry, I assumed that was already the case and didn't think of checking
> that from what I was given, I'll fix the prefix to "iio: core: .." in v2
> 
>> Please run scripts/checkpatch.pl and fix reported warnings. Some
>> warnings can be ignored, but the code here looks like it needs a fix.
>> Feel free to get in touch if the warning is not clear.
> 
> Hm, I did check that and do not get any warning about the code itself:
> 
> $ git show --format=email | ./scripts/checkpatch.pl -q
> WARNING: DT binding docs and includes should be a separate patch. See: Documentation/devicetree/bindings/submitting-patches.rst


> 
> total: 0 errors, 1 warnings, 61 lines checked
> 
> What are you thinking of?

You have warning right there.

> 
> Regarding the dt binding, I'm not actually changing a binding so I
> didn't think of rechecking after adding the note, but I guess it still
> ought to be separate; I'll split it in v2.
> 
>>> For platforms without device trees of_alias_get_id will just fail and
>>> ida_alloc_range will behave as ida_alloc currently does.
>>>
>>> For platforms with device trees, they can not set an alias, for example
>>> this would try to get 10 from the ida for the device corresponding to
>>> adc2:
>>> aliases {
>>>   iio10 = &adc2
>>> };
>>
>> Sorry, that's why you have labels and compatibles.
> 
> I'm not sure I understand this comment -- would you rather this doesn't
> use aliases but instead add a new label (e.g. `iio,index = <10>` or
> whatever) to the iio node itself?

No, the devices already have label property.

> 
> Setting up a fixed alias seems to be precisely what aliases are about
> (e.g. setting rtc0 will make a specific node become /dev/rtc0, same with
> ethernet0, gpio, i2c, mmc, serial...), I'm not sure I agree a new label
> would be more appropriate here, but perhaps I'm missing some context?

Maybe I don't get your point, but your email said "sysfs", so why do you
refer to /dev?

Best regards,
Krzysztof