linux-kernel - Re: [PATCH v4 07/41] drm: handle HAS

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Date:   Tue, 16 May 2023 19:47:18 +0200
From:   "Arnd Bergmann" <arnd@...db.de>
To:     "Thomas Zimmermann" <tzimmermann@...e.de>,
        "Niklas Schnelle" <schnelle@...ux.ibm.com>,
        "Dave Airlie" <airlied@...hat.com>,
        "Gerd Hoffmann" <kraxel@...hat.com>,
        "Dave Airlie" <airlied@...il.com>,
        "Daniel Vetter" <daniel@...ll.ch>
Cc:     Linux-Arch <linux-arch@...r.kernel.org>,
        "Arnd Bergmann" <arnd@...nel.org>,
        "Albert Ou" <aou@...s.berkeley.edu>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "Paul Walmsley" <paul.walmsley@...ive.com>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org,
        virtualization@...ts.linux-foundation.org,
        "Alan Stern" <stern@...land.harvard.edu>,
        spice-devel@...ts.freedesktop.org,
        Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
        "Bjorn Helgaas" <bhelgaas@...gle.com>,
        "Geert Uytterhoeven" <geert@...ux-m68k.org>,
        "Mauro Carvalho Chehab" <mchehab@...nel.org>,
        "Palmer Dabbelt" <palmer@...belt.com>
Subject: Re: [PATCH v4 07/41] drm: handle HAS_IOPORT dependencies

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@...nel.org>
>> Signed-off-by: Arnd Bergmann <arnd@...nel.org>
>> Signed-off-by: Niklas Schnelle <schnelle@...ux.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