linux-kernel - Re: [PATCH v1 3/6] mfd: core: Propagate software node group to the sub devices

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Date:   Tue, 9 Jun 2020 15:40:00 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Lee Jones <lee.jones@...aro.org>
Cc:     Serge Semin <fancer.lancer@...il.com>, linux-gpio@...r.kernel.org,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        linux-kernel@...r.kernel.org,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Subject: Re: [PATCH v1 3/6] mfd: core: Propagate software node group to the
 sub devices

On Mon, Jun 08, 2020 at 08:25:24PM +0100, Lee Jones wrote:
> On Mon, 08 Jun 2020, Andy Shevchenko wrote:
> 
> > From: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> > 
> > When ever device properties are supplied for a sub device, a software node
> > (fwnode) is actually created and then associated with that device. By allowing
> > the drivers to supply the complete software node group instead of just the
> > properties in it, the drivers can take advantage of the other features the
> > software nodes have on top of supplying the device properties.
> > 
> > Signed-off-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> > Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> > ---
> >  drivers/mfd/mfd-core.c   | 31 +++++++++++++++++++++++++++----
> >  include/linux/mfd/core.h |  3 +++
> >  2 files changed, 30 insertions(+), 4 deletions(-)
> 
> I'm not sure a change to the API is justified presently (same does go
> for 'properties' really, but as it was only a couple of lines, it
> didn't seem too intrusive).

This is better and comprehensive API, but I heard you.

> My recommendation is to handle this in-house (i.e. locally in-driver)
> for now.

I think you understand that this is not gonna work (we need to attach fwnode
to the child device before it's registration.

> When (if) more users adopt the practice, then we should
> consider to draw down on line numbers and repetition and make it part
> of the API.

I briefly looked at the current state of affairs and found that properties are
used only for MFD LPSS driver. Would the conversion of that driver to swnodes
work for you?

Note, the long prospective is to get rid of platform_add_properties() API
completely.

-- 
With Best Regards,
Andy Shevchenko