linux-kernel - Re: [PATCH v2 4/4] fbdev: sh_mobile_lcdc: Make FB

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Message-ID: <CAHp75VfTki7r-BMadsmOWudr2nc2f2VYgL9y6xR64usQB70ZAw@mail.gmail.com>
Date: Sat, 27 Dec 2025 16:21:51 +0200
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Chintan Patel <chintanlike@...il.com>
Cc: linux-fbdev@...r.kernel.org, linux-staging@...ts.linux.dev, 
	linux-omap@...r.kernel.org, linux-kernel@...r.kernel.org, 
	dri-devel@...ts.freedesktop.org, tzimmermann@...e.de, andy@...nel.org, 
	deller@....de, gregkh@...uxfoundation.org
Subject: Re: [PATCH v2 4/4] fbdev: sh_mobile_lcdc: Make FB_DEVICE dependency optional

On Fri, Dec 19, 2025 at 7:43 AM Chintan Patel <chintanlike@...il.com> wrote:
>
> The sh_mobile_lcdc driver exposes overlay configuration via sysfs, but the
> core driver does not require CONFIG_FB_DEVICE.
>
> Make sysfs support optional by defining overlay_sysfs_groups as NULL when
> FB_DEVICE is disabled. The driver always sets .dev_groups, and the kernel
> naturally skips NULL attribute groups while the code remains buildable
> and type-checked.

> v2:
> - Replace CONFIG_FB_DEVICE ifdefs with NULL overlay_sysfs_groups
> - Always populate .dev_groups

Same comment about the changelog in the commit messages.

...

> +#ifdef CONFIG_FB_DEVICE
>  ATTRIBUTE_GROUPS(overlay_sysfs);
> +#else
> +/*
> + * When CONFIG_FB_DEVICE is disabled, define overlay_sysfs_groups as NULL.
> + * The compiler will optimize out the sysfs code paths when dev_groups is NULL.
> + */
> +static const struct attribute_group *overlay_sysfs_groups[] = { NULL };
> +#endif

Hmm... I'm wondering if PTR_IF() can anyhow help here.

-- 
With Best Regards,
Andy Shevchenko