linux-kernel - Re: Should regulator core support parsing OF based fwnode?

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Date:   Fri, 4 Oct 2019 12:12:22 +0200
From:   Jean-Jacques Hiblot <jjhiblot@...com>
To:     Jacek Anaszewski <jacek.anaszewski@...il.com>,
        Mark Brown <broonie@...nel.org>
CC:     Sebastian Reichel <sebastian.reichel@...labora.com>,
        <pavel@....cz>, <robh+dt@...nel.org>, <mark.rutland@....com>,
        <lee.jones@...aro.org>, <daniel.thompson@...aro.org>,
        <linux-kernel@...r.kernel.org>, <dri-devel@...ts.freedesktop.org>,
        <tomi.valkeinen@...com>, <dmurphy@...com>,
        <linux-leds@...r.kernel.org>, Liam Girdwood <lgirdwood@...il.com>
Subject: Re: Should regulator core support parsing OF based fwnode?


On 03/10/2019 22:27, Jacek Anaszewski wrote:
> On 10/3/19 9:41 PM, Mark Brown wrote:
>> On Thu, Oct 03, 2019 at 09:21:06PM +0200, Jacek Anaszewski wrote:
>>> On 10/3/19 8:35 PM, Mark Brown wrote:
>>>> On Thu, Oct 03, 2019 at 07:43:17PM +0200, Jacek Anaszewski wrote:
>>>>> On 10/3/19 2:47 PM, Jean-Jacques Hiblot wrote:
>>>>>> On 03/10/2019 12:42, Sebastian Reichel wrote:
>>>>>>> On Thu, Oct 03, 2019 at 10:28:09AM +0200, Jean-Jacques Hiblot wrote:
>>>> This mail has nothing relevant in the subject line and pages of quotes
>>>> before the question for me, it's kind of lucky I noticed it....
>>> Isn't it all about creating proper filters?
>> My point there is that there's nothing obvious in the mail that suggests
>> it should get past filters - just being CCed on a mail isn't super
>> reliable, people often get pulled in due to things like checkpatch or
>> someone copying a CC list from an earlier patch series where there were
>> things were relevant.
> OK, updated the subject.
>
>>>>> I wonder if it wouldn't make sense to add support for fwnode
>>>>> parsing to regulator core. Or maybe it is either somehow supported
>>>>> or not supported on purpose?
>>>> Anything attempting to use the regulator DT bindings in ACPI has very
>>>> serious problems, ACPI has its own power model which isn't compatible
>>>> with that used in DT.
>>> We have a means for checking if fwnode refers to of_node:
>>> is_of_node(const struct fwnode_handle *fwnode)
>>> Couldn't it be employed for OF case?
>> Why would we want to do that?  We'd continue to support only DT systems,
>> just with code that's less obviously DT only and would need to put
>> checks in.  I'm not seeing an upside here.
> For instance few weeks ago we had a patch [0] in the LED core switching
> from using struct device's of_node property to fwnode for conveying
> device property data. And this transition to fwnode property API can be
> observed as a frequent pattern across subsystems.
>
> Recently there is an ongoing effort aiming to add generic support for
> handling regulators in the LED core [1], but it turns out to require
> bringing back initialization of of_node property for
> devm_regulator_get_optional() to work properly.
>
> Support for OF related fwnodes in regulator core could help reducing
> this noise.

We could have this done in dev_of_node():

static inline struct device_node *dev_of_node(struct device *dev)
{
     if (!IS_ENABLED(CONFIG_OF) || !dev)
         return NULL;
     return dev->of_node ? dev->of_node : to_of_node(dev->fwnode);
}

Then it will only be a matter of using dev_of_node() instead of 
accessing directly dev->of_node


>
> [0]
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/leds/led-class.c?id=fd81d7e946c6bdb86dbf0bd88fee3e1a545e7979
> [1]
> https://lore.kernel.org/linux-leds/20190923102059.17818-4-jjhiblot@ti.com/
>