linux-kernel - Re: Regression: 2.6.34 boot fails on E5405 system, bisected: de08e2c26

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Message-ID: <20100714115904.7004be74@virtuousgeek.org>
Date:	Wed, 14 Jul 2010 11:59:04 -0700
From:	Jesse Barnes <jbarnes@...tuousgeek.org>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Ben Greear <greearb@...delatech.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	jacob.jun.pan@...el.com
Subject: Re: Regression:  2.6.34 boot fails on E5405 system, bisected: 
 de08e2c26

On Wed, 14 Jul 2010 11:52:44 -0700
"H. Peter Anvin" <hpa@...or.com> wrote:

> So I suggest the following changes...
> 
> On 07/13/2010 07:19 PM, Jesse Barnes wrote:
> >>
> >> static int fixed_bar_cap(struct pci_bus *bus, unsigned int devfn)
> >> {
> >> 	int pos;
> >> 	u32 pcie_cap = 0, cap_data;
> >> 	printk("fixed_bar_cap, bus: %p  devfn: %u\n", bus, devfn);
> >> 	pos = PCIE_CAP_OFFSET;
> >> 	while (pos) {
> 
> while (pos >= PCIE_CAP_OFFSET) {
> 
> >> 		printk("Before read..\n");
> >> 		if (raw_pci_ext_ops->read(pci_domain_nr(bus), bus->number,
> >> 					  devfn, pos, 4, &pcie_cap))
> >> 			return 0;
> >> 		printk("pcie_cap: %u", pcie_cap);
> >> 		
>    -		if (pcie_cap == 0xffffffff)
>    -			return 0;
> 		
>    +		if (PCI_EXT_CAP_ID(pcie_cap) == 0x0000 ||
>    +		    PCI_EXT_CAP_ID(pcie_cap) == 0xffff)
>    +			break;
> 		
> >> 		printk("Checking vendor..\n");
> 
> >> 		if (PCI_EXT_CAP_ID(pcie_cap) == PCI_EXT_CAP_ID_VNDR) {
> >> 			printk("reading domain_nr\n");
> >> 			raw_pci_ext_ops->read(pci_domain_nr(bus), bus->number,
> >> 					      devfn, pos + 4, 4, &cap_data);
> >> 			printk("cap_data: %u\n", cap_data);
> >> 			if ((cap_data & 0xffff) == PCIE_VNDR_CAP_ID_FIXED_BAR)
> >> 				return pos;
> >> 		}
> >>
> >> 		pos = pcie_cap >> 20;
> 
> 		pos = (pcie_cap >> 20) & 0xffc;
> 
> >> 		printk("pos after shift: %i\n", pos);
> >> 	}
> >>
> >> 	printk("Returning from fixed_bar_cap\n");
> >> 	return 0;
> >> }
> >>
> >>
> > 
> > I thought a related bug was fixed already; the code should be returning
> > all zeros for non-existent BAR reads.

Changes look ok to me, though I'd prefer not hitting this code at all
on non-Moorestown if at all possible.

-- 
Jesse Barnes, Intel Open Source Technology Center
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