On Thu, Oct 25, 2018 at 08:27:18PM +0200, Jacek Anaszewski wrote: > On 10/25/2018 08:07 PM, Dan Murphy wrote: > > Rob > > > > On 10/24/2018 09:54 AM, Rob Herring wrote: > >> On Wed, Oct 24, 2018 at 07:07:57AM -0500, Dan Murphy wrote: > >>> Pavel > >>> > >>> On 10/24/2018 04:04 AM, Pavel Machek wrote: > >>>> Hi! > >>>> > >>>>> The LM3697 is a single function LED driver. The single function LED > >>>>> driver needs to reside in the LED directory as a dedicated LED driver > >>>>> and not as a MFD device. The device does have common brightness and > >>>>> ramp > >>>> > >>>> So it is single function LED driver. That does not mean it can not > >>>> share bindings with the rest. Where the bindings live is not imporant. > >>>> > >>> > >>> It can share bindings that are correctly done, not ones that are > >>> incomplete and incorrect. > >>> > >>> Where bindings live is important to new Linux kernel developers and > >>> product > >>> developers looking for the proper documentation on the H/W bindings. > >>> > >>>>> reside in the Documentation/devicetree/bindings/leds directory and > >>>>> follow the > >>>>> current LED and general bindings guidelines. > >>>> > >>>> What you forgot to tell us in the changelog: > >>> > >>> I can add this to the changelog. > >>> > >>>> > >>>>> +Optional child properties: > >>>>> + - runtime-ramp-up-msec: Current ramping from one brightness > >>>>> level to > >>>>> + the a higher brightness level. > >>>>> + Range from 2048 us - 117.44 s > >>>> > >>>> The other binding uses "ramp-up-msec". Tell us why you are changing > >>>> this, or > >>>> better don't change things needlessly. > >>>> > >>>> We don't want to be using "runtime-ramp-up-msec" for one device and > >>>> "ramp-up-msec" for the other. > >>> > >>> This is another example of how the original bindings were incorrect and > >>> misleading. > >>> > >>> The LM3697 have 2 ramp implementations that can be used. > >>> > >>> Startup/Shutdown ramp and Runtime Ramp. Same Ramp rates different > >>> registers and > >>> different end user experience. > >>> > >>> So having a single node call ramp-up-msec is misleading and it does not > >>> indicate what the H/W will do. > >> > >> The existing ones aren't documented (present in the example is not > >> documented). This seems like something that should be common rather than > >> TI specific. Though it also seems more like something the user would > >> want to control (i.e. sysfs) rather than fixed in DT. > >> > > > > Changing the runtime ramping or startup/shutdown ramping could also be done > > via sysfs. > > I am not dedicated to having it in the DT file I was following prior art. > > > > Jacek > > > > Do you have an opinion on this? > > This is this problem with the Device Tree's scope of responsibility. > It is defined as a means for "describing the hardware", but often > this rule is abused by the properties that fall into "configuration" > category. E.g. default-state, retain-state-suspended from leds-gpio.txt > or linux-default-trigger from common LED bindings. > > In some cases this is justified. The question is whether it is something > that necessarily needs to be configured on driver probing? If not, then > I'd go for sysfs interface.
Yes. I'd also add it should be along the lines of for a given board it's always configured in that way or is it something you'd want in the BIOS of your PC. Rob
