From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Bjorn Helgaas <bhelgaas@google.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Guenter Roeck <linux@roeck-us.net>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"suravee.suthikulpanit@amd.com" <suravee.suthikulpanit@amd.com>,
Will Deacon <Will.Deacon@arm.com>
Subject: Re: [PATCH] PCI: Only enable IO window if supported
Date: Wed, 24 Jun 2015 09:14:43 +1000 [thread overview]
Message-ID: <1435101283.3996.17.camel@kernel.crashing.org> (raw)
In-Reply-To: <CAErSpo6AziA5GXEi6AizW2WP6oLVMd1p57pWunDNBQeVXxp1nw@mail.gmail.com>
On Tue, 2015-06-23 at 18:02 -0500, Bjorn Helgaas wrote:
> On Tue, Jun 23, 2015 at 5:46 PM, Benjamin Herrenschmidt
> <benh@kernel.crashing.org> wrote:
> > On Tue, 2015-06-02 at 15:55 +0100, Lorenzo Pieralisi wrote:
> >> While at it, do you think it is reasonable to also claim the bridge
> >> windows (resources) in the respective pci_read_bridge_* calls ?
> >
> > No, don't claim in read. There's a clear distinction between gathering
> > resources and claiming them, and we need to keep that.
> >
> > Some fixups might happen in between the two for example.
>
> Are there any existing fixups like that? Concrete examples would help
> figure out the best way forward.
Not off the top of my mind, it's been a long time since I wrote the
resource claiming stuff in arch/powerpc but it does make me nervous. We
collect resources when probing and we claim in the survey, those have
been historically very distinct steps.
> Most arches call pci_read_bridge_bases() from pcibios_fixup_bus(). I
> think that's a poor place to do it because it's code that normally
> doesn't have to be arch-specific. Resource claiming is also usually
> done from arch code, and it shouldn't be arch-specific either.
Claiming as in putting in the resource tree etc... is different from
actually reading the values from the HW and is traditionally done much
later, no ?
> If we move both the read and claim into generic code, then we might
> need to make sure there's a fixup phase in between or something.
Well, then there's a more general argument to be made as to whether we
want the claiming to be "merged" as part of the probing/reading I
suppose...
Then there's also the case where everything gets fully reassigned, like
powernv, where the "read" phase is really only about sizing device
BARs...
Cheers,
Ben.
next prev parent reply other threads:[~2015-06-23 23:15 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-23 0:52 [PATCH] PCI: Only enable IO window if supported Guenter Roeck
2015-05-27 21:04 ` Bjorn Helgaas
2015-05-28 2:23 ` Guenter Roeck
2015-05-28 12:41 ` Bjorn Helgaas
2015-06-18 18:01 ` Guenter Roeck
2015-06-18 19:51 ` Bjorn Helgaas
2015-06-18 20:53 ` Guenter Roeck
2015-06-19 16:24 ` Lorenzo Pieralisi
2015-07-07 14:40 ` Lorenzo Pieralisi
2015-07-07 15:01 ` Guenter Roeck
2015-07-07 17:28 ` Lorenzo Pieralisi
2015-07-07 18:13 ` Guenter Roeck
2015-06-02 14:55 ` Lorenzo Pieralisi
2015-06-02 16:32 ` Bjorn Helgaas
2015-06-02 17:02 ` Guenter Roeck
2015-06-02 19:58 ` Bjorn Helgaas
2015-06-03 15:15 ` Guenter Roeck
2015-06-03 10:32 ` Lorenzo Pieralisi
2015-06-03 15:12 ` Guenter Roeck
2015-06-03 16:55 ` Lorenzo Pieralisi
2015-06-03 18:07 ` Guenter Roeck
2015-06-23 22:46 ` Benjamin Herrenschmidt
2015-06-23 23:02 ` Bjorn Helgaas
2015-06-23 23:14 ` Benjamin Herrenschmidt [this message]
2015-06-25 11:27 ` Lorenzo Pieralisi
2015-07-08 8:38 ` Lorenzo Pieralisi
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