Re: [PATCH 6/13] devres: implement managed iomap interface

[Sergei Shtylyov]

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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/