Date: Fri, 14 Aug 2015 11:40:51 -0500
From: Bjorn Helgaas <bhelgaas@google.com>
To: Marc Zyngier <marc.zyngier@arm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Will Deacon <will.deacon@arm.com>,
        Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Grant Likely <grant.likely@linaro.org>,
        Rob Herring <robh+dt@kernel.org>, Alexander Graf <agraf@suse.de>,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linuxppc-dev@lists.ozlabs.org, linux-pci@vger.kernel.org,
        devicetree@vger.kernel.org
Subject: Re: [PATCH v2 2/4] PCI: pci-host-generic: Fix lookup of
 linux,pci-probe-only property
Message-ID: <20150814164051.GF26431@google.com>
References: <1439569159-10051-1-git-send-email-marc.zyngier@arm.com>
 <1439569159-10051-3-git-send-email-marc.zyngier@arm.com>
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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.)

>  	of_id = of_match_node(gen_pci_of_match, np);
>  	pci->cfg.ops = of_id->data;
> -- 
> 2.1.4
> 
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