From: Jacek Anaszewski <jacek.anaszewski@gmail.com>
To: Pavel Machek <pavel@ucw.cz>
Cc: linux-leds@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org, robh@kernel.org,
Baolin Wang <baolin.wang@linaro.org>,
Daniel Mack <daniel@zonque.org>, Dan Murphy <dmurphy@ti.com>,
Linus Walleij <linus.walleij@linaro.org>,
Oleh Kravchenko <oleg@kaa.org.ua>,
Sakari Ailus <sakari.ailus@linux.intel.com>,
Simon Shields <simon@lineageos.org>
Subject: Re: [PATCH 02/24] leds: core: Add support for composing LED class device names
Date: Tue, 13 Nov 2018 21:57:38 +0100 [thread overview]
Message-ID: <09372762-9778-6bf9-0352-7cbee945745f@gmail.com> (raw)
In-Reply-To: <20181112220616.GB11942@amd>
On 11/12/2018 11:06 PM, Pavel Machek wrote:
> On Mon 2018-11-12 21:11:32, Jacek Anaszewski wrote:
>> On 11/12/2018 08:05 PM, Pavel Machek wrote:
>>> Hi!
>>>
>>>>>>> My system looks like this:
>>>>>>>
>>>>>>> input16::capslock tpacpi::bay_active tpacpi::standby
>>>>>>> input16::numlock tpacpi::dock_active tpacpi::thinklight
>>>>>>> input16::scrolllock tpacpi::dock_batt tpacpi::thinkvantage
>>>>>>> input5::capslock tpacpi::dock_status1 tpacpi::unknown_led
>>>>>>> input5::numlock tpacpi::dock_status2 tpacpi::unknown_led2
>>>>>>> input5::scrolllock tpacpi:green:batt tpacpi::unknown_led3
>>>
>>>>> But it is not just for backwards compatibility. See my examples above,
>>>>> it is needed to tell which device the LED is asociated with, and it is
>>>>> absolutely required for USB devices (for example).
>>>>
>>>> For USB devices there is already ledtrig-usbport available, which
>>>> provides sysfs interface for defining and reading the usb ports,
>>>> the status of which the LED indicates. Since the USB devices can be
>>>> attached/removed dynamically, it would be impossible to reflect
>>>> the associations in the LED class device name.
>>>
>>> I'm not talking USB activity. I'm talking USB devices with LEDs on
>>> them, like for example keyboards.
>>>
>>> Please take a look at example above. input16::numlock ;
>>> input5::numlock . You absolutely need device part.
>>
>> It would be redundant since there is "device" symbolic link
>> created in given LED class device sysfs directory, pointing to the
>> corresponding input device directory, like in case of my USB
>> keyboard:
>
> You are right I forgot about the device symlink, and it partly helps
> with the USB keyboard case...
>
> But you still need the device part. Sysfs will not like two
> directories named "::numlock".
LED core has a protection against that. See my reply to Linus.
>
>> #/sys/class/leds/input5::scrolllock$ ls -l
>> total 0
>> -rw-r--r-- 1 root root 4096 Nov 12 20:22 brightness
>> lrwxrwxrwx 1 root root 0 Nov 12 20:22 device -> ../../input5
>> -r--r--r-- 1 root root 4096 Nov 12 20:22 max_brightness
>> drwxr-xr-x 2 root root 0 Nov 12 20:22 power
>> lrwxrwxrwx 1 root root 0 Nov 12 20:04 subsystem ->
>> ../../../../../../../../../../../class/leds
>> -rw-r--r-- 1 root root 4096 Nov 12 20:22 trigger
>
>>> Because userspace needs that information?
>>>
>>> Say you have raid array, with "error" leds for each drive (your list
>>> already contains "hdderr"). Now userland detects problem with hdparm
>>> on /dev/sdi. It would like to turn on corresponding LED.
>>>
>>> How do you propose we do that?
>>
>> Similarly as in case of USB keyboard.
>
> Not really, I'm afraid. Hard drives have no red LEDs on them (and the
> LED would not be visible, anyway) so the "device" symlink in such case
> would point to some kind of i2c LED controller.
>
> Eventually we'll need to have two devices for each LED. "Controller
> this is on" -- in device symlink and "device this talks about".
After thinking it over I agree - we will still need devicename part
Please refer to my reply to Rob.
--
Best regards,
Jacek Anaszewski
next prev parent reply other threads:[~2018-11-13 20:57 UTC|newest]
Thread overview: 105+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-06 22:07 [PATCH 00/24] Add generic support for composing LED class device name Jacek Anaszewski
2018-11-06 22:07 ` [PATCH 01/24] leds: class: Improve LED and LED flash class registration API Jacek Anaszewski
2018-11-07 6:55 ` Baolin Wang
2018-11-07 20:51 ` Jacek Anaszewski
2018-11-08 17:50 ` Dan Murphy
2018-11-08 20:47 ` Jacek Anaszewski
2018-11-11 11:31 ` Pavel Machek
2018-11-06 22:07 ` [PATCH 02/24] leds: core: Add support for composing LED class device names Jacek Anaszewski
2018-11-07 7:20 ` Baolin Wang
2018-11-08 20:47 ` Jacek Anaszewski
2018-11-09 2:35 ` Baolin Wang
2018-11-08 18:06 ` Dan Murphy
2018-11-08 20:48 ` Jacek Anaszewski
2018-11-11 12:02 ` Pavel Machek
2018-11-11 20:02 ` Jacek Anaszewski
2018-11-11 20:16 ` Pavel Machek
2018-11-11 21:14 ` Jacek Anaszewski
2018-11-12 0:01 ` Vesa Jääskeläinen
2018-11-12 15:59 ` Jacek Anaszewski
2018-11-12 21:25 ` Linus Walleij
2018-11-12 22:11 ` LEDs on USB keyboards was " Pavel Machek
2018-11-12 10:35 ` Pavel Machek
2018-11-12 16:01 ` Jacek Anaszewski
2018-11-12 19:05 ` Pavel Machek
2018-11-12 20:11 ` Jacek Anaszewski
2018-11-12 22:06 ` Pavel Machek
2018-11-13 20:57 ` Jacek Anaszewski [this message]
2018-11-13 21:38 ` Geert Uytterhoeven
2018-11-13 21:50 ` Pavel Machek
2018-11-12 21:23 ` Linus Walleij
2018-11-13 19:55 ` Jacek Anaszewski
2018-11-15 9:10 ` Linus Walleij
2018-11-06 22:07 ` [PATCH 03/24] leds: dt-bindings: Add LED_FUNCTION definitions Jacek Anaszewski
2018-11-07 8:36 ` Vokáč Michal
2018-11-07 19:28 ` Jacek Anaszewski
2018-11-08 15:13 ` Rob Herring
2018-11-08 21:03 ` Jacek Anaszewski
2018-11-11 11:31 ` Pavel Machek
2018-11-11 20:02 ` Jacek Anaszewski
2018-11-11 20:20 ` Pavel Machek
2018-11-11 21:16 ` Jacek Anaszewski
2018-11-12 0:25 ` Vesa Jääskeläinen
2018-11-12 16:01 ` Jacek Anaszewski
2018-11-15 9:16 ` Linus Walleij
2018-11-06 22:07 ` [PATCH 04/24] dt-bindings: leds: Add function and color properties Jacek Anaszewski
2018-11-08 18:00 ` Dan Murphy
2018-11-08 20:47 ` Jacek Anaszewski
2018-11-08 21:08 ` Dan Murphy
2018-11-09 20:00 ` Jacek Anaszewski
2018-11-09 8:32 ` Vesa Jääskeläinen
2018-11-09 20:42 ` Jacek Anaszewski
2018-11-10 17:19 ` Vesa Jääskeläinen
2018-11-12 16:02 ` Jacek Anaszewski
2018-11-13 7:10 ` Vesa Jääskeläinen
2018-11-13 19:02 ` Jacek Anaszewski
[not found] ` <5bea0eb8.1c69fb81.6b921.80e6@mx.google.com>
2018-11-13 20:57 ` Jacek Anaszewski
2018-11-27 20:37 ` Jacek Anaszewski
2018-11-30 14:38 ` Rob Herring
2018-11-30 21:08 ` Pavel Machek
2018-11-30 22:19 ` Rob Herring
2018-12-01 21:17 ` Jacek Anaszewski
2018-12-11 17:27 ` Rob Herring
2018-12-11 22:44 ` Pavel Machek
2018-12-21 10:12 ` Linus Walleij
2018-12-12 9:59 ` Pavel Machek
2018-12-12 13:56 ` Rob Herring
2018-12-12 18:32 ` Pavel Machek
2018-12-23 20:11 ` Jacek Anaszewski
2018-11-06 22:07 ` [PATCH 05/24] dt-bindings: sc27xx-blt: " Jacek Anaszewski
2018-11-11 14:29 ` Pavel Machek
2018-11-11 20:03 ` Jacek Anaszewski
2018-11-06 22:07 ` [PATCH 06/24] leds: sc27xx-blt: Use led_compose_name() Jacek Anaszewski
2018-11-07 7:22 ` Baolin Wang
2018-11-11 14:31 ` Pavel Machek
2018-11-06 22:07 ` [PATCH 07/24] dt-bindings: lt3593: Add function and color properties Jacek Anaszewski
2018-11-06 22:07 ` [PATCH 08/24] leds: lt3593: Use led_compose_name() Jacek Anaszewski
2018-11-07 19:37 ` Daniel Mack
2018-11-07 19:49 ` Jacek Anaszewski
2018-11-08 8:33 ` Daniel Mack
2018-11-06 22:07 ` [PATCH 09/24] dt-bindings: lp8860: Add function and color properties Jacek Anaszewski
2018-11-08 18:01 ` Dan Murphy
2018-11-06 22:07 ` [PATCH 10/24] leds: lp8860: Use led_compose_name() Jacek Anaszewski
2018-11-08 18:16 ` Dan Murphy
2018-11-08 20:48 ` Jacek Anaszewski
2018-11-12 14:05 ` Dan Murphy
2018-11-06 22:07 ` [PATCH 11/24] dt-bindings: lm3692x: Add function and color properties Jacek Anaszewski
2018-11-08 18:12 ` Dan Murphy
2018-11-06 22:07 ` [PATCH 12/24] leds: lm3692x: Use led_compose_name() Jacek Anaszewski
2018-11-08 18:14 ` Dan Murphy
2018-11-08 20:48 ` Jacek Anaszewski
2018-11-08 21:11 ` Dan Murphy
2018-11-11 14:31 ` Pavel Machek
2018-11-06 22:07 ` [PATCH 13/24] dt-bindings: lm36010: Add function and color properties Jacek Anaszewski
2018-11-08 18:15 ` Dan Murphy
2018-11-06 22:07 ` [PATCH 14/24] leds: lm3601x: Use led_compose_name() Jacek Anaszewski
2018-11-06 22:07 ` [PATCH 15/24] dt-bindings: cr0014114: Add function and color properties Jacek Anaszewski
2018-11-06 22:07 ` [PATCH 16/24] leds: cr0014114: Use led_compose_name() Jacek Anaszewski
2018-11-06 22:07 ` [PATCH 17/24] dt-bindings: aat1290: Add function and color properties Jacek Anaszewski
2018-11-06 22:07 ` [PATCH 18/24] leds: aat1290: Use led_compose_name() Jacek Anaszewski
2018-11-06 22:07 ` [PATCH 19/24] dt-bindings: as3645a: Add function and color properties Jacek Anaszewski
2018-11-06 22:07 ` [PATCH 20/24] leds: as3645a: Use led_compose_name() Jacek Anaszewski
2018-11-06 22:07 ` [PATCH 21/24] dt-bindings: leds-gpio: Add function and color properties Jacek Anaszewski
2018-11-06 22:07 ` [PATCH 22/24] leds: gpio: Use led_compose_name() Jacek Anaszewski
2018-11-06 22:07 ` [PATCH 23/24] dt-bindings: an30259a: Add function and color properties Jacek Anaszewski
2018-11-06 22:07 ` [PATCH 24/24] leds: an30259a: Use led_compose_name() Jacek Anaszewski
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