linux-kernel - Re: [PATCH v4 1/4] video: fbdev: atyfb: only use ioremap

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Message-Id: <74915109-446a-4c1f-91bc-95dc6e3be200@app.fastmail.com>
Date:   Wed, 08 Mar 2023 22:34:57 +0100
From:   "Arnd Bergmann" <arnd@...db.de>
To:     "Luis Chamberlain" <mcgrof@...nel.org>,
        "Baoquan He" <bhe@...hat.com>
Cc:     linux-kernel@...r.kernel.org,
        Linux-Arch <linux-arch@...r.kernel.org>, linux-mm@...ck.org,
        "Michael Ellerman" <mpe@...erman.id.au>,
        "Geert Uytterhoeven" <geert@...ux-m68k.org>,
        "Christoph Hellwig" <hch@...radead.org>,
        "Helge Deller" <deller@....de>,
        "Thomas Zimmermann" <tzimmermann@...e.de>,
        "Christophe Leroy" <christophe.leroy@...roup.eu>,
        linux-fbdev@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v4 1/4] video: fbdev: atyfb: only use ioremap_uc() on i386 and ia64

0On Wed, Mar 8, 2023, at 21:01, Luis Chamberlain wrote:
> On Wed, Mar 08, 2023 at 09:07:07PM +0800, Baoquan He wrote:
>> From: Arnd Bergmann <arnd@...db.de>
>> 
>> ioremap_uc() is only meaningful on old x86-32 systems with the PAT
>> extension, and on ia64 with its slightly unconventional ioremap()
>> behavior, everywhere else this is the same as ioremap() anyway.
>> 
>> Change the only driver that still references ioremap_uc() to only do so
>> on x86-32/ia64 in order to allow removing that interface at some
>> point in the future for the other architectures.
>> 
>> On some architectures, ioremap_uc() just returns NULL, changing
>> the driver to call ioremap() means that they now have a chance
>> of working correctly.
>> 
>> Signed-off-by: Arnd Bergmann <arnd@...db.de>
>> Signed-off-by: Baoquan He <bhe@...hat.com>
>> Cc: Helge Deller <deller@....de>
>> Cc: Thomas Zimmermann <tzimmermann@...e.de>
>> Cc: Christophe Leroy <christophe.leroy@...roup.eu>
>> Cc: linux-fbdev@...r.kernel.org
>> Cc: dri-devel@...ts.freedesktop.org
>
> Reviewed-by: Luis Chamberlain <mcgrof@...nel.org>
>
> Is anyone using this driver these days? How often do fbdev drivers get
> audited to see what can be nuked?

Geert already mentioned that this one is likely used on old
powermac systems. I think my arm boardfile removal orphaned
some other fbdev drivers though. I removed the ones that can
no longer be enabled, but think a bunch of other ones
are still selectable but have no platform_device definition
or DT support: FB_PXA168, FB_DA8XX, FB_MX3, and MMP_FB.

These four platforms are all still supported with DT, but
over time it gets less likely that anyone is still interested
in adding DT support to the fbdev drivers.

    Arnd