You got a little bit wrong. I just used monitor to give an example that I have a separate PC whose monitor provides this feature. I actually want to implement it for the display of my laptop. I'll just do it for my driver though. I guess it's already hardware specific in the first place.
On Thu 27 Aug, 2015 12:00 am Kenneth Adam Miller < [email protected]> wrote: > Well, to do that you would have to read the specifications of the > particular hardware. In which case the driver becomes specialized to it-not > useful for anything but your own monitor. But if your monitor provides that > support, then I guess when the ioctl receives a requested change in > brightness you could use that facility of the monitor to retain the setting. > > On Wed, Aug 26, 2015 at 2:16 PM, Umair Khan <[email protected]> wrote: > >> >> >> On Wed, Aug 26, 2015 at 11:21 PM, Kenneth Adam Miller < >> [email protected]> wrote: >> >>> Well, it's probably worth doing for the sake of your learning. However, >>> if you are going to get into the source, I think it's highly likely that >>> you are going to see that the driver provides such a feature to userspace >>> code through means of an ioctl, and in that case, you will probably be able >>> to set the brightness programmatically without ever having to interfere >>> with the driver code itself. So for that matter, the objective doesn't >>> really fit with the complexity you're taking on. If what I'm saying is >>> right, you could easily implement this entirely in userland code by writing >>> a binary and then putting a script in the startup execution so that it >>> calls your binary. >>> >>> If you really want to hack the driver, another way to do it is to just >>> put the brightness setting in the driver's init function, so that when the >>> module is loaded it turns up the brightness. In that case, you *should* get >>> what you want because the driver will be loaded at system boot. >>> >>> On Wed, Aug 26, 2015 at 1:45 PM, Umair Khan <[email protected]> wrote: >>> >>>> Hello everyone, >>>> >>>> I've been thinking of writing a patch a lot lately. But with my level >>>> of knowledge I cannot do something groundbreaking. >>>> One thing which came to my mind is to write a patch related to the >>>> driver which controls the brightness of the display. >>>> What happens now is I lower down the brightness, and when I restart the >>>> laptop, it's back to the highest amount. >>>> I'm using Ubuntu 14.04 LTS on top of Linux Kernel 4.2 rc3+. >>>> I was thinking of writing the current brightness to sysfs and read that >>>> value when the driver is started during the boot. >>>> >>>> So, my question is that is it already implemented in the driver and >>>> just that Ubuntu resets it on every reboot from userspace ? >>>> And if it is not implemented, is it worth implementing ? >>>> >>>> Thanks >>>> Umair >>>> Delhi, India >>>> >>>> >>>> >>> >> I do get this that, most probably this feature would have been provided >> via ioctl. And it is better handled inside the userspace. >> But it'd be just like the hardware is intelligent enough to keep the >> value persistent across reboot. Like the monitor of my PC keeps the >> brightness, and all the different values for that matter, persistent across >> reboot. >> Userspace can always override this behavior anyways. >> >> Thoughts ? >> > >
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