On Thursday, November 16, 2017 4:42 PM, Dan Murphy wrote: > > Jacek > > On 11/16/2017 02:14 PM, Jacek Anaszewski wrote: > > Hi Dan and Pavel, > > > > On 11/15/2017 11:23 PM, Pavel Machek wrote: > >> Hi! > >> > >>>> Shouldn't the driver be targeted for backlight subsystem then? > >>>> > >>>> Adding backlight maintainers. > >>>> > >>> > >>> Great point! I was not aware of the backlight subsystem. > >>> > >>> Looks like I need to create a back light version as well. > >>> > >>> Like the lp8788 did since this can be used as a LED driver beyond > >>> display back lighting. > >> > >> No, definitely not two drivers for lp8788 hardware. > > > > I agree. > > > >> If that does not yet exist... you want to create glue layer to be able > >> to use LED as a display backlight. (It may already exist, no idea). > >> > >> ... > >> > >> Actually or maybe a LED trigger. Just set LED's trigger to "this is > >> display backlight". > > > > There is one already: > > > > drivers/leds/trigger/ledtrig-backlight.c > > > > It adds a LED class device to the fb_notifier_list > > (drivers/video/fbdev/core/fb_notify.c) > > > > using fb_register_client(). The same is used in > > backlight_device_register (drivers/video/backlight/backlight.c). > > > > Actually why do you want to have this driver in the LED subsystem, > > if it is advertised as "designed for LCD display backlighting"? > > Well this is also advertised as a driver for Smart phone and tablet > devices. And having worked with the Android lighting > solutions this is the preferred subsystem for Android. The Android OS > manages the led brightness based on ALS values and in > turn calls into the driver to control the brightness register through the > vendor provided lighting HAL. > > I am going to look at the backlight source to figure out how to get the > same functionality using the backlight subsystem. > Otherwise I will plug in this driver to the backlight subsystem through > the notifier. I also developed Android devices for a long time. I think that modifying HAL will not be difficult. Also, backlight subsystem will be similar with LED subsystem. You can grasp it easily. Best regards, Jingoo Han > > > > > As a side note I can say that I've been always wondering why the two > > subsystems for similar type of hardware. > > This is my worry too. Why do we need both subsystems to do the same thing? > > I don't see either having one advantage over the other. > > > Dan > > > > > -- > ------------------ > Dan Murphy -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
