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SubjectRe: [PATCH 6/13] devres: implement managed iomap interface
Kumar Gala wrote:

>>>>> Those functions are going to break on 32-bit platforms with
>>>>> extended physical address (well, that's starting with Pentiums
>>>>> which had 36-bit PAE :-) AND devices mapped beyond 4 GB (e.g.
>>>>> PowerPC 44x). You should have used resource_size_t for the
>>>>> 'offset' parameter. As this most probably means that libata is
>>>>> broken on such platforms, I'm going to submit a patch...

>>> It's broken with drivers using MMIO, I meant to say.

>> Oops, I meant PCI drivers here, at least for the time being. And it
>> looks like that was a false alarm. :-]

>>>> Yeah, right please go ahead. But I wonder whether any BIOS was
>>>> actually crazy enough to map mmio region above 4G on 32bit machine.

>>> This is a *hardware* mapping on some non-x86 platforms (like PPC
>>> 44x or MIPS Alchemy). The arch/ppc/ and arch/mips/ kernels have
>>> special hooks called from ioremap() which help create an illusion
>>> that the PCI memory space on such platforms (not only it) is mapped
>>> below 4 GB; arch/powerpc/ kernel doesn't do this anymore -- hence
>>> this newly encountered issue.

>> I thought that pcim_iomap() used devm_ioremap() or something --
>> which of course turned to be wrong. devm_ioremap() alone is yet safe
>> since there are no users for it amongst PPC 44x platform device
>> drivers...

> but there is no reason not to make it work properly. For example I
> believe libata uses devm_* and the fsl SATA driver (non-PCI) will need
> to work in cases similar to the 44x.

Well, as for sata_fsl, it calls of_iomap() which does The Right Thing.

> - k

WBR, Sergei


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