Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755520AbbHNQvL (ORCPT ); Fri, 14 Aug 2015 12:51:11 -0400 Received: from mx2.suse.de ([195.135.220.15]:45892 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755285AbbHNQvJ convert rfc822-to-8bit (ORCPT ); Fri, 14 Aug 2015 12:51:09 -0400 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2104\)) Subject: Re: [PATCH v2 2/4] PCI: pci-host-generic: Fix lookup of linux,pci-probe-only property From: Alexander Graf In-Reply-To: <20150814164324.GC22809@arm.com> Date: Fri, 14 Aug 2015 09:50:54 -0700 Cc: Bjorn Helgaas , Marc Zyngier , Ben Herrenschmidt , Paul Mackerras , Michael Ellerman , Suravee Suthikulpanit , Lorenzo Pieralisi , "grant.likely@linaro.org" , Rob Herring , "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" Content-Transfer-Encoding: 8BIT Message-Id: References: <1439569159-10051-1-git-send-email-marc.zyngier@arm.com> <1439569159-10051-3-git-send-email-marc.zyngier@arm.com> <20150814164051.GF26431@google.com> <20150814164324.GC22809@arm.com> To: Will Deacon X-Mailer: Apple Mail (2.2104) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2766 Lines: 68 > On 14.08.2015, at 09:43, Will Deacon 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 >>> --- >>> 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/