Re: Should regulator core support parsing OF based fwnode?

[Jean-Jacques Hiblot]

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@xxxxxx/