From: bhelgaas@google.com (Bjorn Helgaas)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 2/4] PCI: pci-host-generic: Fix lookup of linux,pci-probe-only property
Date: Fri, 14 Aug 2015 15:26:21 -0500 [thread overview]
Message-ID: <CAErSpo5abs2Qj25Bs+JVg87ve346f_RVz7jhNwqdv856+WvXQA@mail.gmail.com> (raw)
In-Reply-To: <20150814164324.GC22809@arm.com>
On Fri, Aug 14, 2015 at 11:43 AM, Will Deacon <will.deacon@arm.com> wrote:
> On Fri, Aug 14, 2015 at 05:40:51PM +0100, Bjorn Helgaas wrote:
>> On Fri, Aug 14, 2015 at 05:19:17PM +0100, Marc Zyngier wrote:
>> > When pci-host-generic looks for the probe-only property, it seems
>> > to trust the DT to be correctly written, and assumes that there
>> > is a parameter to the property.
>> >
>> > Unfortunately, this is not always the case, and some firmware expose
>> > this property naked. The driver ends up making a decision based on
>> > whatever the property pointer points to, which is likely to be junk.
>> >
>> > Switch to the common of_pci.c implementation that doesn't suffer
>> > from this problem.
>> >
>> > Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
>> > ---
>> > drivers/pci/host/pci-host-generic.c | 9 +--------
>> > 1 file changed, 1 insertion(+), 8 deletions(-)
>> >
>> > diff --git a/drivers/pci/host/pci-host-generic.c b/drivers/pci/host/pci-host-generic.c
>> > index 265dd25..545ff4e 100644
>> > --- a/drivers/pci/host/pci-host-generic.c
>> > +++ b/drivers/pci/host/pci-host-generic.c
>> > @@ -210,7 +210,6 @@ static int gen_pci_probe(struct platform_device *pdev)
>> > int err;
>> > const char *type;
>> > const struct of_device_id *of_id;
>> > - const int *prop;
>> > struct device *dev = &pdev->dev;
>> > struct device_node *np = dev->of_node;
>> > struct gen_pci *pci = devm_kzalloc(dev, sizeof(*pci), GFP_KERNEL);
>> > @@ -225,13 +224,7 @@ static int gen_pci_probe(struct platform_device *pdev)
>> > return -EINVAL;
>> > }
>> >
>> > - prop = of_get_property(of_chosen, "linux,pci-probe-only", NULL);
>> > - if (prop) {
>> > - if (*prop)
>> > - pci_add_flags(PCI_PROBE_ONLY);
>> > - else
>> > - pci_clear_flags(PCI_PROBE_ONLY);
>> > - }
>> > + of_pci_check_probe_only(of_chosen);
>>
>> Do we need support for pci-probe-only in pci-host-generic at all?
>> You're removing the use in amd-overdrive.dts, and there are no other
>> DTs in the kernel tree that mention it.
>>
>> If we can live without it, that would be nice. It seems like a relic from
>> days when we couldn't reliably assign resources. (I'm not saying we can do
>> that reliably even today, but I'd rather make it reliable than turn it
>> off.)
>
> Kvmtool certainly uses it (and generates its own DT, hence why you don't
> see it in mainline). Not sure about qemu, though.
Do you know why kvmtool wants probe-only? Would something break if we
didn't support probe-only? I guess we'd be looking for a case where
Linux assigns resources and that assignment doesn't work with kvmtool?
"pci-probe-only" doesn't appear in qemu
(git://git.qemu-project.org/qemu.git). (I guess Alexander confirmed
that later.)
Alexander wrote:
> QEMU definitely doesn't do proble-only.
> Is this driver used on real PPC machines too?
I think you're asking about pci-host-generic.c, and the answer is
"no," because pci-host-generic.c currently depends on CONFIG_ARM.
Bjorn
next prev parent reply other threads:[~2015-08-14 20:26 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-14 16:19 [PATCH v2 0/4] PCI: arm64/powerpc: Fix parsing of linux, pci-probe-only Marc Zyngier
2015-08-14 16:19 ` [PATCH v2 1/4] of/pci: Add of_pci_check_probe_only to parse "linux, pci-probe-only" Marc Zyngier
2015-08-14 21:08 ` Rob Herring
2015-09-02 22:23 ` [PATCH v2 1/4] of/pci: Add of_pci_check_probe_only to parse "linux,pci-probe-only" Bjorn Helgaas
2015-09-03 8:18 ` [PATCH v2 1/4] of/pci: Add of_pci_check_probe_only to parse "linux, pci-probe-only" Marc Zyngier
2015-08-14 16:19 ` [PATCH v2 2/4] PCI: pci-host-generic: Fix lookup of linux, pci-probe-only property Marc Zyngier
2015-08-14 16:40 ` [PATCH v2 2/4] PCI: pci-host-generic: Fix lookup of linux,pci-probe-only property Bjorn Helgaas
2015-08-14 16:43 ` Will Deacon
2015-08-14 16:50 ` [PATCH v2 2/4] PCI: pci-host-generic: Fix lookup of linux, pci-probe-only property Alexander Graf
2015-08-14 20:26 ` Bjorn Helgaas [this message]
2015-08-17 9:01 ` [PATCH v2 2/4] PCI: pci-host-generic: Fix lookup of linux,pci-probe-only property Will Deacon
2015-08-14 16:45 ` Will Deacon
2015-08-14 16:19 ` [PATCH v2 3/4] powerpc: PCI: Fix lookup of linux, pci-probe-only property Marc Zyngier
2015-08-14 16:19 ` [PATCH v2 4/4] arm64: dts: Drop linux, pci-probe-only from the Seattle DTS Marc Zyngier
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