Thread (92 messages) 92 messages, 9 authors, 2014-07-25

Re: [PATCH v8 3/9] pci: Introduce pci_register_io_range() helper function.

From: Liviu Dudau <hidden>
Date: 2014-07-02 14:23:09
Also in: linux-arm-kernel, linux-pci, lkml

On Wed, Jul 02, 2014 at 01:30:31PM +0100, Arnd Bergmann wrote:
On Tuesday 01 July 2014 21:45:09 Liviu Dudau wrote:
quoted
On Tue, Jul 01, 2014 at 09:36:10PM +0200, Arnd Bergmann wrote:
quoted
On Tuesday 01 July 2014 19:43:28 Liviu Dudau wrote:

This still conflicts with the other allocator you have in patch 9
for pci_remap_iospace: nothing guarantees that the mapping is the
same for both.

Also, this is a completely pointless exercise at this moment, because
nobody cares about the result of pci_address_to_pio on architectures
that don't already provide this function. If we ever get a proper
Open Firmware implementation that wants to put hardcoded PCI devices
into DT, we can add an implementation, but for now this seems overkill.

The allocator in pci_register_io_range seems reasonable, why not merge
this function with pci_remap_iospace() as I have asked you multiple
times before? Just make it return the io_offset so the caller can
put that into the PCI host resources.
Hi Arnd,

While I agree with you that at some moment the allocators were inconsistent
wrt each other, for this version I would respectfully disagree on this.
The allocator in pci_register_io_range() only makes sure that the ranges
are not overlapping, it doesn't do any mapping whatsoever, while
pci_remap_iospace() does only an ioremap_page_range(). The idea is that
you get the offset out of pci_address_to_pio() and apply it to
pci_remap_iospace().
Ok, got it now, I'm sorry I didn't read this properly at first.

Your solution looks correct to me, just using different
tradeoffs to what I was expecting: You get a working pci_address_to_pio()
function, which is probably never needed, but in turn you need to
keep the state of each host bridge in a global list.
Just a reminder that with my patchset I *do* start using pci_address_to_pio()
in order to correctly parse the IO ranges from DT.

Best regards,
Liviu
	Arnd
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