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Re: [PATCH] leds: Introduce userspace leds driver

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  Re: [PATCH] leds: Introduce userspace leds driver Pavel Machek <pavel@ucw.cz> - 2016-09-15 14:50 +0200
    Re: [PATCH] leds: Introduce userspace leds driver Jacek Anaszewski <j.anaszewski@samsung.com> - 2016-09-15 17:00 +0200

#1484125 — Re: [PATCH] leds: Introduce userspace leds driver

Hi!

> Thanks for the patch. It is very nice. I have only one minor remark
> in the code.
> 
> I think that it would be good to add a documentation for this
> driver to Documentation/leds, with exemplary C program instead
> of python one. The program could poll the dev node in a loop,
> which allows to conveniently check the impact of setting particular
> triggers and all other brightness change events.

Actually, I'd say that python is fine -- it is used heavily in tools/.

But perhaps the example program should go to tools/?

> >def change_brightness(b):
> >    with open('/sys/class/leds/{}/brightness'.format(name) , 'w') as f:
> >       f.write(str(b))
> >
> >
> >with open('/dev/uleds', 'rb+', 0) as uleds:
> >    bname = name.encode("ascii")
> >    # create the leds class device
> >    uleds.write(bname + b'\0' * (ULEDS_MAX_NAME_SIZE - len(bname)))

Umm. I don't see it in the kernel code. You let userspace provide a
LED name?

Where is the LED name tested for sanity? I guess there could be a lot
of fun naming a led ".." for example...

Best regards,
								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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#1484266

Hi Pavel,

On 09/15/2016 02:41 PM, Pavel Machek wrote:
> Hi!
>
>> Thanks for the patch. It is very nice. I have only one minor remark
>> in the code.
>>
>> I think that it would be good to add a documentation for this
>> driver to Documentation/leds, with exemplary C program instead
>> of python one. The program could poll the dev node in a loop,
>> which allows to conveniently check the impact of setting particular
>> triggers and all other brightness change events.
>
> Actually, I'd say that python is fine -- it is used heavily in tools/.
>
> But perhaps the example program should go to tools/?

I see python scripts only in perf tools. Let's stay by C application.

David, could you please prepare another version of the patch, that
splits test app code to the separate file in tools/leds (the directory
doesn't exist so far), also providing suitable Makefile?

>>> def change_brightness(b):
>>>    with open('/sys/class/leds/{}/brightness'.format(name) , 'w') as f:
>>>       f.write(str(b))
>>>
>>>
>>> with open('/dev/uleds', 'rb+', 0) as uleds:
>>>    bname = name.encode("ascii")
>>>    # create the leds class device
>>>    uleds.write(bname + b'\0' * (ULEDS_MAX_NAME_SIZE - len(bname)))
>
> Umm. I don't see it in the kernel code. You let userspace provide a
> LED name?
>
> Where is the LED name tested for sanity? I guess there could be a lot
> of fun naming a led ".." for example...

Good point.

-- 
Best regards,
Jacek Anaszewski

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