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Date:   Tue, 16 May 2023 19:47:18 +0200
From:   "Arnd Bergmann" <arnd@arndb.de>
To:     "Thomas Zimmermann" <tzimmermann@suse.de>,
        "Niklas Schnelle" <schnelle@linux.ibm.com>,
        "Dave Airlie" <airlied@redhat.com>,
        "Gerd Hoffmann" <kraxel@redhat.com>,
        "Dave Airlie" <airlied@gmail.com>,
        "Daniel Vetter" <daniel@ffwll.ch>
Cc:     Linux-Arch <linux-arch@vger.kernel.org>,
        "Arnd Bergmann" <arnd@kernel.org>,
        "Albert Ou" <aou@eecs.berkeley.edu>,
        "Rafael J . Wysocki" <rafael@kernel.org>,
        "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
        "Paul Walmsley" <paul.walmsley@sifive.com>,
        linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
        dri-devel@lists.freedesktop.org,
        virtualization@lists.linux-foundation.org,
        "Alan Stern" <stern@rowland.harvard.edu>,
        spice-devel@lists.freedesktop.org,
        =?UTF-8?Q?Uwe_Kleine-K=C3=B6nig?= <u.kleine-koenig@pengutronix.de>,
        "Bjorn Helgaas" <bhelgaas@google.com>,
        "Geert Uytterhoeven" <geert@linux-m68k.org>,
        "Mauro Carvalho Chehab" <mchehab@kernel.org>,
        "Palmer Dabbelt" <palmer@dabbelt.com>
Subject: Re: [PATCH v4 07/41] drm: handle HAS_IOPORT dependencies
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On Tue, May 16, 2023, at 19:13, Thomas Zimmermann wrote:
>
> Am 16.05.23 um 13:00 schrieb Niklas Schnelle:
>> In a future patch HAS_IOPORT=n will result in inb()/outb() and friends
>> not being declared. We thus need to add HAS_IOPORT as dependency for
>> those drivers using them. In the bochs driver there is optional MMIO
>> support detected at runtime, warn if this isn't taken when
>> HAS_IOPORT is not defined.
>> 
>> There is also a direct and hard coded use in cirrus.c which according to
>> the comment is only necessary during resume.  Let's just skip this as
>> for example s390 which doesn't have I/O port support also doesen't
>> support suspend/resume.
>> 
>> Co-developed-by: Arnd Bergmann <arnd@kernel.org>
>> Signed-off-by: Arnd Bergmann <arnd@kernel.org>
>> Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
>> ---
>> Note: The HAS_IOPORT Kconfig option was added in v6.4-rc1 so
>>        per-subsystem patches may be applied independently
>> 
>>   drivers/gpu/drm/qxl/Kconfig   |  1 +
>>   drivers/gpu/drm/tiny/bochs.c  | 17 +++++++++++++++++
>>   drivers/gpu/drm/tiny/cirrus.c |  2 ++
>
> There are more invocations in gma500. See[1]
>
> [1] 
> https://elixir.bootlin.com/linux/v6.3/source/drivers/gpu/drm/gma500/cdv_device.c#L30

GMA500 already has "depends on X86", so I don't think
any changes are needed there -- x86 is already highly dependent
on I/O ports for a number of reasons.

     Arnd