Re: [Fwd: Re: [PATCH 4/5]PCI: x86 MMCONFIG: introduce pcibios_fix_bus_scan()]

[Tony Camuso <tcamuso@redhat.com>]

Greg KH wrote:

> But you never answered my questions about _who_ would be responding to
> those log messages about reporting things...
> 
> thanks,
> 
> greg k-h

I did.

I said I would remove that string, because I don't want all that email,
either. It's a little past the middle of the post appended here.

-------- Original Message --------
Subject: Re: [PATCH 4/5]PCI: x86 MMCONFIG: introduce pcibios_fix_bus_scan()
Date: Wed, 19 Dec 2007 19:17:42 -0500
From: Tony Camuso <tcamuso@redhat.com>
Reply-To: tcamuso@redhat.com
To: Greg KH <gregkh@suse.de>
References: <20071219221746.20362.39243.sendpatchset@dhcp83-188.boston.redhat.com> 
<20071219221806.20362.25964.sendpatchset@dhcp83-188.boston.redhat.com> <20071219231032.GC24219@suse.de>

Greg,

First, let me thank you for your prompt replies!

Greg KH wrote:
 > On Wed, Dec 19, 2007 at 05:18:06PM -0500, tcamuso@redhat.com wrote:
 >> commit ab28e1157e970f711c8451b66b3f940ec092db9d
 >> Author: Tony Camuso <tony.camuso@hp.com>
 >> Date:   Wed Dec 19 15:51:48 2007 -0500
 >>
 >>     Introduces the x86 arch-specific routine that will determine whether
 >>     a device responds correctly to MMCONFIG accesses. This routine is
 >>     given the generic name pcibios_fix_bus_scan_quirk()
 >>
 >>     The comment at the top of the routine explains its logic.
 >>
 >>     Signed-off-by: Tony Camuso tony.camuso@hp.com
 >>
 >> diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
 >> index 8627463..9b1742d 100644
 >> --- a/arch/x86/pci/common.c
 >> +++ b/arch/x86/pci/common.c
 >> @@ -525,3 +525,64 @@ struct pci_bus *pci_scan_bus_with_sysdata(int busno)
 >>
 >>  	return bus;
 >>  }
 >> +
 >> +/**
 >> + * This routine traps devices not correctly responding to MMCONFIG access.
 >> + * For each device on the current bus, compare a mmconf read of the
 >> + * vendor/device dword with a legacy PCI config read. If they're not the same,
 >> + * the bus serving this device must use legacy PCI config accesses instead of
 >> + * mmconf, as must all buses descending from this bus.
 >> + */
 >> +
 >> +#define CHECK_MMCFG_STR_1 \
 >> +	"PCI: Device at %04x:%02x.%02x.%x is not MMCONFIG compliant.\n"
 >> +#define CHECK_MMCFG_STR_2 \
 >> +	"PCI: Bus %04x:%02x and its descendents cannot use MMCONFIG.\n"
 >
 > Why define these if they are only used in one place?

If you object, I will be happy to move them into the routine body
without the defines. I agree that It does look inconsistent to have
these strings defined and other strings embedded in the routine body.

 >
 > Also, as you use dev_info(), I think you are duplicating some of the
 > information in the resulting printk(), right?
 >
Actually, no. The strings do not contain redundant info. The pr_info
routine is just a macro for printk(KERN_INFO ...)

 >> +
 >> +void __devinit pcibios_fix_bus_scan_quirk(struct pci_bus *bus)
 >> +{
 >> +	int devfn;
 >> +	int fail;
 >> +	int found_nommconf_dev = 0;
 >> +	static int advised;
 >> +	u32 mcfg_vendev;
 >> +	u32 arch_vendev;
 >> +	struct pci_ops *save_ops = bus->ops;
 >> +
 >> +	if (bus->parent != NULL)
 >> +		if (bus->parent->ops == &pci_legacy_ops)
 >> +			return;
 >> +
 >> +	if (!advised) {
 >> +		pr_info("PCI: If a device isn't working, try \"pci=nommconf\". "
 >> +			"If that helps, please post a report.\n");
 >
 > Post a report where?  Who is going to handle these reports?
 >
 > The last time someone put a line like this in the kernel, I got a ton of
 > email and didn't know what to do with it.  If you really are trusting of
 > this patch, please put your email address in this printk(), so that you
 > can properly handle the resulting reports.  I sure don't want to :)

Hmmm! Good point! I was actually copying that other message. I will
remove the string that advises posting a report. I sure don't want 'em,
and I can see that you don't, either.
:)

 >
 >> +		advised = 1;
 >> +	}
 >> +	pr_debug("PCI: Checking bus %04x:%02x for MMCONFIG compliance.\n",
 >> +		 pci_domain_nr(bus), bus->number);
 >> +
 >> +	for (devfn = 0; devfn < 256; devfn++) {
 >> +		bus->ops = &pci_legacy_ops;
 >> +		fail = (pci_bus_read_config_dword(bus, devfn, PCI_VENDOR_ID,
 >> +						  &arch_vendev));
 >
 > What's with the extra () around the function?

The function call used to be contained in an if statement.
I changed the logic, but forgot to remove the extra parens.
It's tough getting old.
:}

 >
 >> +		if ((arch_vendev == 0xFFFFFFFF) || (arch_vendev == 0) || fail)
 >> +			continue;
 >> +
 >> +		bus->ops = save_ops;	/* Restore to original value */
 >> +		pci_bus_read_config_dword(bus, devfn, PCI_VENDOR_ID,
 >> +					  &mcfg_vendev);
 >> +		if (mcfg_vendev != arch_vendev) {
 >> +			found_nommconf_dev = 1;
 >> +			break;
 >> +		}
 >> +	}
 >> +
 >> +	if (found_nommconf_dev) {
 >> +		pr_info(CHECK_MMCFG_STR_1, pci_domain_nr(bus), bus->number,
 >> +			PCI_SLOT(devfn), PCI_FUNC(devfn));
 >> +		pr_info(CHECK_MMCFG_STR_2, pci_domain_nr(bus), bus->number);
 >> +		bus->ops = &pci_legacy_ops;	/* Use Legace PCI Config */
 >
 > Spelling check for your comments :)
 >
 > thanks,
 >
 > greg k-h

Oops Legace ... too much language confusion in my life ... portugues ...
italian ... oi ...