From mboxrd@z Thu Jan  1 00:00:00 1970
From: Liviu Dudau <Liviu.Dudau@arm.com>
Subject: Re: [PATCH v7 3/3] arm64: Add architecture support for PCI
Date: Thu, 20 Mar 2014 12:50:04 +0000
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To: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <Catalin.Marinas@arm.com>, linux-pci <linux-pci@vger.kernel.org>, Bjorn Helgaas <bhelgaas@google.com>, Will Deacon <Will.Deacon@arm.com>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, linaro-kernel <linaro-kernel@lists.linaro.org>, LKML <linux-kernel@vger.kernel.org>, "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>, LAKML <linux-arm-kernel@lists.infradead.org>, Tanmay Inamdar <tinamdar@apm.com>, Grant Likely <grant.likely@secretlab.ca>
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On Thu, Mar 20, 2014 at 12:26:02PM +0000, Arnd Bergmann wrote:
> On Thursday 20 March 2014, Liviu Dudau wrote:
> > > I don't even understand why you want to create a generic pci_addr=
ess_to_pio
> > > implementation, when we don't need that for arm64 at all. Unless =
I'm
> > > missing something important, that function is only called in case=
 of
> > > PCI_PROBE_DEVTREE with pci_of_scan on PowerPC. I don't expect any
> > > architecture to do the same thing, and the only other architectur=
e that
> > > needs something like it (sparc) has a different implementation.
> >=20
> > Because in my [v7 2/6]* patch for the generic host bridge support I=
 start
> > using pci_address_to_pio to fix the conversion of PCI ranges to res=
ources.
> > That requires an arm64 (or more correctly, an arch with memory mapp=
ed IO
> > specific) version of pci_address_to_pio().
>=20
> Yes, but why do you use it there?

I'm parsing the device tree and have reached the PCI IO range for the h=
ost bridge.
There is no host bridge created yet for that and hence no mapping. I ne=
ed to
take the DT range declaration that gives me   CPU start .. SIZE --> BUS=
 start and
convert it into   Logical IO port start .. Logical IO port end. While I=
 could've
come up with (yet) another function that does the conversion from CPU a=
ddress to
port IO address, I thought it would be nice to use the existing pci_add=
ress_to_pio()
function and adapt it to my needs. It has a __weak implementation anywa=
y so I
could overwrite it in the architecture code.

To me it looked like a good plan and we had some discussions around my =
initial
goofy mistake of using pci_addr as physical address for translation. I =
never
thought it was considered a bad idea.

Best regards,
Liviu

>=20
> 	Arnd
>=20

--=20
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
| I would like to |
| fix the world,  |
| but they're not |
| giving me the   |
 \ source code!  /
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    =C2=AF\_(=E3=83=84)_/=C2=AF