> On 14.08.2015, at 09:43, Will Deacon <will.deacon@xxxxxxx> 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@xxxxxxx>
>>> ---
>>> 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.
QEMU definitely doesn't do proble-only. Is this driver used on real PPC machines too? In that case you also won't see the dt, because it comes with the hardware ;).
Alex
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