On Mon 2019-03-11 09:36:20, Nick Crews wrote: > On Fri, Mar 8, 2019 at 3:13 PM Pavel Machek <pa...@ucw.cz> wrote: > > > > Hi! > > > > > > This patch is meant to be applied on top of the for-next > > > > branch of the platform/chrome repository, as it uses some of > > > > the code staged there. > > > > > > > > The EC is in charge of controlling the keyboard backlight on > > > > the Wilco platform. We expose a standard LED class device at > > > > /sys/class/leds/wilco::kbd_backlight. This driver is modeled > > > > after the standard Chrome OS keyboard backlight driver at > > > > drivers/platform/chrome/cros_kbd_led_backlight.c > > > > > > > > Some Wilco devices do not support a keyboard backlight. This > > > > is checked in probe(), and in this case the sysfs entry will > > > > not appear, and everything will behave normally. > > > > > > It would be even better if we did not register platform device if EC > > > does not support backlight. > > Good point Dmitry. That would require making the core driver > dependent upon this keyboard backlight driver, though. Do you > think that added complexity is worth it? I don't see performance > concerns with adding one unused platform device, so is your rationale > that it would just be cleaner code? >
You probably wanted to mail dmitry. You should have probably cc-ed
Dmitry and the lists.
> > > > + data->led.brightness_set = keyboard_led_set_brightness;
> > > > + data->led.brightness_get = keyboard_led_get_brightness;
> > >
> > > wilco_ec_mailbox() may sleep, so you need to assign it to
> > > led.brightness_set_blocking.
> >
> > Hmm. Seeing get method there... can the EC change the brightness
> > without command from kernel?
>
> No, the EC won't change the brightness without getting told to by
> the kernel. Do you think that means that we could get away with just
> caching the brightness from the previous set_brightness(), and not
> actually sending a mailbox) command to the EC on get_brightness()?
Something like that. Even better ... don't implement brightness_get at
all, and check that core does the right thing checking it.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures)
http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
signature.asc
Description: Digital signature
