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Date:   Mon, 17 Apr 2023 11:22:24 +0200
From:   "Arnd Bergmann" <arnd@arndb.de>
To:     "Thomas Zimmermann" <tzimmermann@suse.de>,
        "Geert Uytterhoeven" <geert@linux-m68k.org>
Cc:     "Daniel Vetter" <daniel.vetter@ffwll.ch>,
        "Helge Deller" <deller@gmx.de>,
        "Javier Martinez Canillas" <javierm@redhat.com>,
        "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
        Linux-Arch <linux-arch@vger.kernel.org>,
        linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org,
        linux-snps-arc@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org,
        loongarch@lists.linux.dev, linux-m68k@lists.linux-m68k.org,
        linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org,
        linuxppc-dev@lists.ozlabs.org, linux-sh@vger.kernel.org,
        sparclinux@vger.kernel.org, x86@kernel.org
Subject: Re: [PATCH v2 01/19] fbdev: Prepare generic architecture helpers
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On Mon, Apr 17, 2023, at 11:03, Thomas Zimmermann wrote:
> Am 11.04.23 um 10:08 schrieb Geert Uytterhoeven:
>> On Thu, Apr 6, 2023 at 4:30=E2=80=AFPM Thomas Zimmermann <tzimmermann=
@suse.de> wrote:

>>> +#ifndef fb_pgprotect
>>> +#define fb_pgprotect fb_pgprotect
>>> +static inline void fb_pgprotect(struct file *file, struct vm_area_s=
truct *vma,
>>> +                               unsigned long off)
>>=20
>> Does this affect any noMMU platforms that relied on fb_pgprotect()
>> doing nothing before?
>> Perhaps the body below should be protected by "#ifdef CONFIG_MMU"?
>
> I cannot conclusively answer this question, but I did some grep'ing=20
> ('git grep ndef | grep CONFIG_MMU'):
>
> Only the architectures in this patchset provide <asm/fb.h> but nothing=20
> anywhere uses <asm-generic/fb.h> yet. And of those architectures, only=20
> arm and m68k have !CONFIG_MMU cases. Those are handled in the rsp=20
> patches. I think we're good.

Agreed. The generic version is just a more elaborate way to do
nothing here, as the=20

     vma->vm_page_prot =3D pgprot_writecombine(vma->vm_page_prot);

line on nommu just turns into a self-assignment of the same member
that was set the line before.

     Arnd