Hi Greg, On Mon, 4 Oct 2021 08:37:37 +0200 Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > On Sun, Oct 03, 2021 at 10:53:38PM +0200, Marek Behún wrote: > > Hello Greg, > > > > could you give your opinion on this discussion? > > What discussion? Top posting ruins that :( Sorry, the discussion is here https://lore.kernel.org/linux-leds/20211001144053.3952474a@thinkpad/T/ But the basic question is below, so you don't need to read the discussion. > > Are device names (as returned by dev_name() function) also part of > > sysfs ABI? Should these names be stable across reboots / kernel > > upgrades? > > Stable in what exact way? Example: - Board has an ethernet PHYs that is described in DT, and therefore has stable sysfs path (derived from DT path), something like /sys/devices/.../mdio_bus/f1072004.mdio-mii/f1072004.mdio-mii:01 - The PHY has a subnode describing a LED. The LED subsystem has a different naming scheme (it uses DT node name as a last resort). When everything is okay, the dev_name() of the LED will be something like ethphy42:green:link - Now suppose that the PHY driver is unloaded and loaded again. The PHY sysfs path is unchanged, but the LED will now be named ethphy43:green:link Is this OK? > Numbering of devices (where a dynamic value is part of a name, like the > "42" in "usb42"), is never guaranteed to be stable, but the non-number > part of the name (like "usb" is in "usb42") is stable, as that is what > you have properly documented in the Documentation/ABI/ files defining > the bus and class devices, right? It does make sense for removable devices like USB. What I am asking is whether it is also OK for devices that have stable DT nodes. Marek
