linux-kernel - Re: [PATCH v1 1/4] backlight: hx8357: Make use of device properties

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Message-ID: <20240122103530.GC8596@aspen.lan>
Date: Mon, 22 Jan 2024 10:35:30 +0000
From: Daniel Thompson <daniel.thompson@...aro.org>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: Javier Martinez Canillas <javierm@...hat.com>,
	dri-devel@...ts.freedesktop.org, linux-fbdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, Jingoo Han <jingoohan1@...il.com>,
	Lee Jones <lee@...nel.org>, Helge Deller <deller@....de>
Subject: Re: [PATCH v1 1/4] backlight: hx8357: Make use of device properties

On Sun, Jan 21, 2024 at 03:48:05PM +0200, Andy Shevchenko wrote:
> On Mon, Jan 15, 2024 at 09:20:46AM +0100, Javier Martinez Canillas wrote:
> > Andy Shevchenko <andriy.shevchenko@...ux.intel.com> writes:
>
> ...
>
> > > +typedef int (*hx8357_init)(struct lcd_device *);
> >
> > This kind of typedef usage is frowned upon in the Linux coding style [0]
> > (per my understanding at least) and indeed in my opinion it makes harder
> > to grep.
> >
> > [0] https://www.kernel.org/doc/Documentation/process/coding-style.rst
>
> Thanks for pointing this out. However, this piece does _not_ clarify typedef:s
> for function pointers which I personally find a good to have.
>
> ...
>
> > > -	ret = ((int (*)(struct lcd_device *))match->data)(lcdev);
> >
> > This is what I mean, before it was clear what was stored in match->data.
> > But after you changes, what is returned by the device_get_match_data()
> > function is opaque and you need to look at the typedef hx8357_init to
> > figure that out.
>
> The above is so ugly in my opinion, that justifies using typedef:s even
> if you are quite skeptical about them.

FWIW I was pretty skeptical about it to. Largely because the three
touchs (typedef, variable initialization, use) spread things
around a bit too much.

Can we at least name the type to make it obvious that it is a function
pointer? Something like hx8357_init_fn .


Daniel.