On Tue, Oct 08, 2019 at 09:47:31AM +0200, Pavel Machek wrote: > Hi! > > > > > > I don't understand. The original commit broke userspace operations. > > > > > Shouldn't it be reverted, or fixed this way in order to have userspace > > > > > work properly again? > > > > > > > > So, what it is exactly that is not working? :-). Yes, root can > > > > disconnect LED from v4l2 interface; he can also connect it > > > > back. Documentation says that happens. > > > > > > > > Yes, root can do stupid things. > > > > > > > > Commit 0013b23d66a2768f5babbb0ea9f03ab067a990d8 is from 2008. I'd > > > > prefer we did not apply it in 2008, but... > > > > > > Ah, my fault, I thought this was a new commit. > > > > > > Guru, what are you doing here that this is required all of a sudden? No > > > other kernel seems to need these changes, what is different in your > > > Android userspace that requires this patch series? > > > > > > thanks, > > > > > > greg k-h > > > > Hi Greg, > > > > Our camera flash driver first requests the available current from the > > flash LED before setting its brightness. It passes a trigger as argument > > to the function that determines the available current. This function > > uses trigger_to_lcdev() to look up the led_classdev associated with that > > trigger as a first step. This lookup will fail if the trigger has been > > dissociated from its led_classdev as a result of a user setting that > > led_classdev's brightness to zero manually through sysfs. > > > > Why would the user set the brightness to zero? The user does this as > > part of camera and LED testing activities which include, amongst other > > things, visual inspection of the operation of various onboard LEDs. The > > user uses sysfs to manually turn on and off the LEDs by setting their > > brightness to max and then to zero in order to verify that they are > > working as expected. > > Yes, so you should really set trigger to none before changing > brightness manually and restore it back to whatever it was when you > are done with manual testing. Hi Pavel, Tried your suggestion to set the trigger to "none" before manual testing and to restore it afterwards, and it works. Thanks a lot.
