Re: [PATCH v2] Documentation: leds: Add description of LED Flash class extension

[Jacek Anaszewski <j.anaszewski@samsung.com>]

Hi Pavel,

On 02/12/2015 06:44 PM, Pavel Machek wrote:
> Hi!
>
>>>> You acked LED Flash class patch, didn't you? :)
>>>>
>>>> There are many attributes documented in the list fashion, e.g.:
>>>> available_frequencies in the Documentation/ABI/testing/sysfs-class-devfreq.
>>>
>>> No, sorry, you can't do this. We have this parsing nightmare in /proc,
>>> before, and we don't want it again.
>>>
>>>> If we changed this a bit it would be easily parsed with AWK:
>>>>
>>>> echo "0 none;1 max77693-led1;2 max77693-led2" | awk -F';' '{ for (i=1;
>>>> i<=NF; i++) print $i}' | awk '{print $1": "$2}'
>>>
>>> sysfs is one entry per file. If someone screwed it up in devfreq, it
>>> is not reason to screw it up here. (Space separated lists of integers
>>> might be acceptable. Fixed strings with one marked by []s happen,
>>> too. Maps between ints and names are not.)
>>
>> "Fixed strings with one marked by []s happen" - I don't quite
>> get this.
>
> root@duo:~# cat /sys/power/state
> freeze mem disk
> root@duo:~# cat /sys/power/disk
> [platform] shutdown reboot suspend
> root@duo:~#
>
>> Could you propose the acceptable format then?
>> The numbers alone are inconvenient to use, we need a human
>> readable description next to them. Or some another way
>> to obtain the name.
>
> Files like "0.active", "0.name", "1.active", "1.name"?
>
> Subdirectories 0/1 with "name" and "active" files?

We have flash_sync_strobe attribute which allows to read currently
chosen sync_led. I would simplify this:

Let's assume there are two LED Flash class deviecs:

- max77693-flash1
- max77693-flash2

Proposed design described by use cases:

#cd /sys/class/leds/max77693-flash1
#cat available_flash_leds
#[0.none] 1.max77693-flash2
#cat flash_sync_strobe
#0.none
#echo 1 > flash_sync_strobe
#cat flash_sync_strobe
#1.max77693-flash2
#cat available_sync_leds
#0.none [1.max77693-flash2]


-- 
Best Regards,
Jacek Anaszewski