linux-kernel - Re: [PATCH v1 1/2] mfd: lm3533: Hide legacy platform data in the driver

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Message-ID: <ZmBcvtLCzllQDWVX@hovoldconsulting.com>
Date: Wed, 5 Jun 2024 14:40:30 +0200
From: Johan Hovold <johan@...nel.org>
To: Lee Jones <lee@...nel.org>
Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	linux-kernel@...r.kernel.org,
	Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH v1 1/2] mfd: lm3533: Hide legacy platform data in the
 driver

On Fri, May 31, 2024 at 05:58:34PM +0100, Lee Jones wrote:
> On Fri, 31 May 2024, Andy Shevchenko wrote:
> 
> > On Fri, May 31, 2024 at 04:54:45PM +0100, Lee Jones wrote:
> > > On Fri, 31 May 2024, Andy Shevchenko wrote:
> > > > On Fri, May 31, 2024 at 04:00:48PM +0100, Lee Jones wrote:
> > > > > On Wed, 08 May 2024, Andy Shevchenko wrote:
> > > > > 
> > > > > > First of all, there is no user for the platform data in the kernel.
> > > > > > Second, it needs a lot of updates to follow the modern standards
> > > > > > of the kernel, including proper Device Tree bindings and device
> > > > > > property handling.
> > > > > > 
> > > > > > For now, just hide the legacy platform data in the driver's code.
> > > > > 
> > > > > Why not just rip it out entirely?
> > > > 
> > > > You mean the driver?
> > > 
> > > The unused platform data.
> > 
> > Good question. In any case these drivers are non-functional anyway without OOT
> > board code. If we rip out the main platform data completely, the logical following
> > question arises: why do we need the per-device platform data? If we rip that out,
> > we basically make non-functional driver a 100% dead code. Hence what you propose
> > mostly equals to ripping out the drivers completely.
> > 
> > TL;DR: with the main platform data being ripped out the driver code will be in
> > inconsistent state.
> 
> What do you think Johan?  Do you see any reason to keep it around?

Yeah, I'd prefer to keep it around. This device is used in a bunch of
Sony phones and Bjorn A posted a series adding devicetree bindings a few
years ago which I believe was more or less acked and ready go.

I'll try to find some time to look at that myself as I think I may
favour a less verbose binding (e.g. similar to pm8008 that I'm working
on).

For now I suggest keeping the platform data where it is and just convert
the single gpio lookup to look for a "hwen" gpio that can be provided by
lookup tables and soon devicetree.

Johan