linux-kernel - Re: [PATCH v3 4/4] fbdev: sh_mobile_lcdc: Make FB

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Message-ID: <aVkWigAQWC1dZBAv@smile.fi.intel.com>
Date: Sat, 3 Jan 2026 15:15:54 +0200
From: Andy Shevchenko <andriy.shevchenko@...el.com>
To: Helge Deller <deller@....de>
Cc: Chintan Patel <chintanlike@...il.com>, Helge Deller <deller@...nel.org>,
	andy <andy@...nel.org>, linux-fbdev@...r.kernel.org,
	linux-omap@...r.kernel.org, linux-kernel@...r.kernel.org,
	dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v3 4/4] fbdev: sh_mobile_lcdc: Make FB_DEVICE dependency
 optional

On Sat, Jan 03, 2026 at 10:59:44AM +0100, Helge Deller wrote:
> On 12/30/25 19:25, Chintan Patel wrote:
> > On 12/30/25 00:13, Helge Deller wrote:

...

> > > > -ATTRIBUTE_GROUPS(overlay_sysfs);
> > > 
> > > Instead of replacing the ^ ATTRIBUTE_GROUPS() by the code below,
> > > isn't it possible to just mark the overlay_sysfs_attrs[] array
> > > _maybe_unused, and just do:
> > > + #ifdef CONFIG_FB_DEVICE
> > > + ATTRIBUTE_GROUPS(overlay_sysfs);
> > > + #endif
> > > 
> > > ?
> > 
> > Yes, the __maybe_unused + #ifdef ATTRIBUTE_GROUPS() approach would work.
> > 
> > I went with the PTR_IF(IS_ENABLED()) pattern because Andy suggested
> > using PTR_IF() to conditionally include overlay_sysfs_group in
> > overlay_sysfs_groups, and to keep .dev_groups always populated while
> > letting the device core skip NULL groups. This avoids conditional
> > wiring via #ifdef and keeps the code type-checked without
> > CONFIG_FB_DEVICE.
> > If you still prefer the simpler #ifdef ATTRIBUTE_GROUPS() approach
> > for this driver, I can switch to that, but I wanted to follow Andy’s
> > guidance here.
> 
> I assume Andy will agree to my suggested approach, as it's cleaner
> and avoids code bloat/duplication. Maybe you send out a v4 with my
> suggested approach, then it's easier to judge... ?

I'm also fine with original code. But a suggested approach would work as well
(at least like it sounds from the above description). Ideally would be nice to
get rid of ifdeffery completely (that's why we have PTR_IF() for), although
it might be not so readable. TL;DR: the most readable solution is the winner.

-- 
With Best Regards,
Andy Shevchenko