Subject: Re: [GIT PULL 1/2] asm-generic: rework PCI I/O space access
To:     Niklas Schnelle <schnelle@linux.ibm.com>,
        Arnd Bergmann <arnd@kernel.org>
CC:     Linus Torvalds <torvalds@linux-foundation.org>,
        linux-arch <linux-arch@vger.kernel.org>,
        linux-pci <linux-pci@vger.kernel.org>,
        "Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>
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From:   John Garry <john.garry@huawei.com>
Message-ID: <3d543c90-383f-647a-5cd4-f7fd4e7246ad@huawei.com>
Date:   Tue, 21 Dec 2021 16:48:57 +0000
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On 20/12/2021 09:27, Niklas Schnelle wrote:
>>   > My feeling is that in this case we want some other dependency, e.g. a
>>   > new CONFIG_LPC. It should actually be possible to use this driver on
>>   > any machine with an LPC bus, which would by definition be the primary
>>   > I/O space, so it should be possible to load it on Arm64.
>>
>> You did suggest HARDCODED_IOPORT earlier in this thread, and the
>> definition/premise there seemed sensible to me.
>>
>> Anyway it seems practical to make all these changes in a single series,
>> so need a way forward as Niklas has no such changes for this additional
>> kconfig option.
>>
>> As a start, may I suggest we at least have Niklas' patch committed to a
>> dev branch based on -next or latest mainline release for further analysis?
>>
>> Thanks,
>> John
>>
>>
> My plan would be to split the patch up into more manageable pieces as
> suggested by Arnd plus of course fixes like the missing ARM select. As
> Arnd suggested I'll split the HAS_IOPORT additions into the initial
> introduction plus arch selects and then the HAS_IOPORT dependencies per
> subsytem. I think these per subsystem dependency patches then would be
> a great place to find drivers which should have a different dependency
> be it on LPC or a newly introduced HARDCODED_IOPORT. The thing is we
> can find and check HAS_IOPORT dependencies easily but it's hard to find
> HARDCODED_IOPORT so I think the lattter should be a refinement of the
> former. It can of course still go in as a single series. I'll
> definitely make the next iteration available as a git branch.

I'll do an audit for what would require HARDCODED_IOPORT to understand 
the scope while you can continue the work on your current path.

Thanks,
john