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
