Jacek On 10/25/2018 01:27 PM, 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. > Appreciate the feedback. I think you and Rob are right. This should be a sysfs entry. I can think of instances where the ramp times might want to be modified or even turned off. I will change that implementation. Dan -- ------------------ Dan Murphy
