From: Dan Murphy <dmurphy@ti.com>
To: Jacek Anaszewski <jacek.anaszewski@gmail.com>,
Rob Herring <robh@kernel.org>
Cc: Pavel Machek <pavel@ucw.cz>, <devicetree@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, <linux-leds@vger.kernel.org>,
<lee.jones@linaro.org>, <tony@atomide.com>
Subject: Re: [PATCH v4 2/7] dt-bindings: ti-lmu: Modify dt bindings for the LM3697
Date: Thu, 25 Oct 2018 13:32:00 -0500 [thread overview]
Message-ID: <dfee9293-490f-2d47-c75b-971735683d41@ti.com> (raw)
In-Reply-To: <ade3121a-58ab-c0c3-6605-cf7d6a638da0@gmail.com>
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
next prev parent reply other threads:[~2018-10-25 18:32 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-23 17:06 [PATCH v4 1/7] leds: add TI LMU backlight driver Dan Murphy
2018-10-23 17:06 ` [PATCH v4 2/7] dt-bindings: ti-lmu: Modify dt bindings for the LM3697 Dan Murphy
2018-10-24 9:04 ` Pavel Machek
2018-10-24 12:07 ` Dan Murphy
2018-10-24 13:43 ` Pavel Machek
2018-10-24 14:54 ` Rob Herring
2018-10-25 18:07 ` Dan Murphy
2018-10-25 18:27 ` Jacek Anaszewski
2018-10-25 18:32 ` Dan Murphy [this message]
2018-10-25 19:54 ` Rob Herring
2018-10-26 8:30 ` Pavel Machek
2018-10-26 8:37 ` Pavel Machek
2018-10-30 13:40 ` Dan Murphy
2019-03-02 23:07 ` Pavel Machek
2019-03-04 19:14 ` Dan Murphy
2018-10-24 14:49 ` Rob Herring
2018-10-25 17:56 ` Dan Murphy
2018-10-23 17:06 ` [PATCH v4 3/7] mfd: ti-lmu: Remove support for LM3697 Dan Murphy
2018-10-23 17:06 ` [PATCH v4 4/7] leds: lm3697: Introduce the lm3697 driver Dan Murphy
2018-10-23 17:06 ` [PATCH v4 5/7] dt-bindings: ti-lmu: Modify dt bindings for the LM3633 Dan Murphy
2018-10-24 9:23 ` Pavel Machek
2018-10-24 14:35 ` Rob Herring
2018-10-24 18:38 ` Pavel Machek
2018-10-24 21:50 ` Rob Herring
2018-10-25 18:01 ` Dan Murphy
2018-10-23 17:06 ` [PATCH v4 6/7] mfd: ti-lmu: Remove support for LM3633 Dan Murphy
2018-10-23 17:06 ` [PATCH v4 7/7] leds: lm3633: Introduce the lm3633 driver Dan Murphy
2018-10-24 9:14 ` [PATCH v4 1/7] leds: add TI LMU backlight driver Pavel Machek
2018-10-24 12:27 ` Dan Murphy
2018-10-24 13:17 ` Pavel Machek
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