From: Arnd Bergmann <arnd@arndb.de>
To: linux-arm-kernel@lists.infradead.org
Cc: Liviu Dudau <liviu@dudau.co.uk>, Sinan Kaya <okaya@codeaurora.org>,
        linaro-kernel <linaro-kernel@lists.linaro.org>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Device Tree ML <devicetree@vger.kernel.org>,
        linux-pci <linux-pci@vger.kernel.org>,
        Jingoo Han <jg1.han@samsung.com>, Liviu Dudau <Liviu.Dudau@arm.com>,
        LKML <linux-kernel@vger.kernel.org>, Will Deacon <Will.Deacon@arm.com>,
        Grant Likely <grant.likely@secretlab.ca>,
        Kukjin Kim <kgene.kim@samsung.com>, Tanmay Inamdar <tinamdar@apm.com>,
        Suravee Suthikulanit <suravee.suthikulpanit@amd.com>,
        Catalin Marinas <Catalin.Marinas@arm.com>,
        Bjorn Helgaas <bhelgaas@google.com>
Subject: Re: [PATCH v8 3/9] pci: Introduce pci_register_io_range() helper function.
Date: Wed, 02 Jul 2014 14:30:31 +0200
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On Tuesday 01 July 2014 21:45:09 Liviu Dudau wrote:
> On Tue, Jul 01, 2014 at 09:36:10PM +0200, Arnd Bergmann wrote:
> > 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.

	Arnd
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