On 03/02/16 18:51, Bjorn Helgaas wrote: > On Wed, Feb 03, 2016 at 06:32:20PM +0000, Jake Oshins wrote: >>> -----Original Message----- >>> From: Bjorn Helgaas [mailto:helgaas@xxxxxxxxxx] >>> Sent: Wednesday, February 3, 2016 10:25 AM >>> To: Jake Oshins <jakeo@xxxxxxxxxxxxx> >>> Cc: gregkh@xxxxxxxxxxxxxxxxxxx; KY Srinivasan <kys@xxxxxxxxxxxxx>; linux- >>> kernel@xxxxxxxxxxxxxxx; devel@xxxxxxxxxxxxxxxxxxxxxx; Haiyang Zhang >>> <haiyangz@xxxxxxxxxxxxx>; marc.zyngier@xxxxxxx; >>> bhelgaas@xxxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx >>> Subject: Re: [PATCH RESEND 1/3] PCI: Add fwnode_handle to pci_sysdata >>> >>> Hi Jake, >>> >>> On Tue, Feb 02, 2016 at 05:41:41PM +0000, jakeo@xxxxxxxxxxxxx wrote: > >>>> diff --git a/include/linux/pci.h b/include/linux/pci.h index >>>> 27df4a6..cd05a8e 100644 >>>> --- a/include/linux/pci.h >>>> +++ b/include/linux/pci.h >>>> @@ -1515,6 +1515,10 @@ static inline int pci_get_new_domain_nr(void) { >>>> return -ENOSYS; } >>>> >>>> #include <asm/pci.h> >>>> >>>> +#ifndef pci_root_bus_fwnode >>>> +#define pci_root_bus_fwnode(bus) ((void)(bus), NULL) >>> >>> Huh, interesting. This is new for me; I guess the idea is that we at least >>> evaluate "bus" even when pci_root_bus_fwnode isn't defined, so the >>> compiler can catch egregious errors? >>> >> >> This was a suggestion by Mark Zyngier. It made the non-x86 architectures build benignly. If you'd like it done differently, I'm open to suggestion. I don't remember suggesting the use of the comma operator, but just to check that pci_root_bus_fwnode wasn't previously defined. > Something like "#define pci_root_bus_fwnode(bus) NULL" would be > typical. What I'm curious about is the use of the comma operator. > I'm not opposed to it; I'm just trying to understand why it makes a > difference. I guess it flags the variable as used, and prevents an overly sensitive compiler from being loud and obnoxious... Just a guess though. M. -- Jazz is not dead. It just smells funny... -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
