On Fri, Jan 18, 2019 at 10:07:05AM +0100, Uwe Kleine-König wrote: > On Fri, Jan 18, 2019 at 09:56:52AM +0100, Greg Kroah-Hartman wrote: > > On Fri, Jan 11, 2019 at 05:29:45PM +0100, Christian Lamparter wrote: > > > The patch "usb: simplify usbport trigger" together with "leds: triggers: > > > add device attribute support" caused an regression for the usbport > > > trigger. it will no longer enumerate any active usb hub ports under the > > > "ports" directory in the sysfs class directory, if the usb host drivers > > > are fully initialized before the usbport trigger was loaded. > > > > > > The reason is that the usbport driver tries to register the sysfs > > > entries during the activate() callback. And this will fail with -2 / > > > ENOENT because the patch "leds: triggers: add device attribute support" > > > made it so that the sysfs "ports" group was only being added after the > > > activate() callback succeeded. > > > > > > This version of the patch reverts parts of the "usb: simplify usbport > > > trigger" patch and restores usbport trigger's functionality. > > > > This feels like going backwards, as a driver should not be adding and > > removing sysfs groups, because you race with userspace. Userspace has > > no idea that the new sysfs files were added or removed, right? > > I think this is not an issue as the led trigger core code calls > kobject_uevent_env() when the trigger is set. Ok, that helps a lot then. > But I still agree that there seems to be something "unusual" about the > usb led trigger ... > > Instead of providing a sysfs-file per port to make said port trigger the > led, I'd prefer a single file that you can use to add and remove ports > from the trigger. With this change the driver can properly benefit from > the attribute handling of the led-trigger core and is more in line with > the other triggers. But how do you know how many ports are present? And this feels like it ends up being a "custom api" for each different type of led that is present in the system. Or is that already the case? thanks, greg k-h
