On Fri, Sep 18, 2020 at 12:52:58AM +0200, Marek Behun wrote: > Hi, Hi Marek, > > the leds-ns2 kernel driver has allows 3 modes for a LED: > OFF, ON and blinking on SATA activity > > This third mode is activated via another sysfs file in the LED device > sysfs directory: /sys/class/leds/<LED>/sata. > > Since we now support LED private HW triggers, it would be better if > this was rewritten to use this new API. It sounds like a great idea. > > The question is how many people use this mode and may complain if we > change this sysfs ABI? Not a lot IMHO. This LED devices are found in some LaCie/Seagate NAS. Most of them, such as the Seagate NAS 4-Bay (Marvell Armada 370 SoC) are supported by the Debian distribution. For the users I have been in contact with, I am pretty confident they should be able to deal with this changes. They already dealt with worse. Another user is the Seagate NAS distribution. And this user will be happy to switch to the new ABI. > > Another question is whether the LED supports another HW blinking mode, > or just SATA? How is this wired on the board? Three different LED modes are available: off, on and SATA activity blinking. The LED modes are controlled through two GPIOs (command and slow): each combination of values for the command/slow GPIOs corresponds to a LED mode. For an example, have a look at the leds-ns2 DT node in the armada-370-seagate-nas-4bay.dts file. The only hardware blinking mechanism for this LED device is SATA. Basically the SATA blinking signal is built from the SATA pin activity of the HDD. This signal is a little bit reworked by some electronic components in order to produce a blinking rate OK for the human eye. Hope this helps. Simon
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