[REGRESSION][PRECISE] LP:961482 Added To Kernel Team Hot List

[Joseph Salisbury]

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On 03/22/2012 11:15 AM, Joseph Salisbury wrote:
> Hello,
> 
> I've added the following bug to the Kernel Team Hot List:
> LP:961482[0]
> 
> 	* This is a regression between 3.2.0-18 and 3.2.0-19 that prevents the
> system from booting.
> 	* One duplicate so far.
> 	* I'll kick of a bisect to try and identify the offending commit.
> 
> If anyone has some free cycles, it would be great if this bug could be
> reviewed.
> 
> Thanks,
> 
> Joe
> 
> 
> 
> 
> [0] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/961482
> 



Some bisecting and testing was performed.  The bad commit which caused
this regression appears to be:

f043ddb60c84ea64a23b755004572afe922e653c PCI: ignore pre-1.1 ASPM
quirking when ASPM is disabled
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 1cfbf22..24f049e 100644
- --- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -500,6 +500,9 @@ static int pcie_aspm_sanity_check(struct pci_dev *pdev)
        int pos;
        u32 reg32;

+       if (aspm_disabled)
+               return 0;
+
        /*
         * Some functions in a slot might not all be PCIe functions,
         * very strange. Disable ASPM for the whole slot


Building a test kernel with this commit reverted allows the machines to
boot.  There has already been some discussion on this commit
upstream[0], and I reported this bug upstream as well[1].

Thanks,

Joe

[0] https://lkml.org/lkml/2012/3/19/408
[1] https://lkml.org/lkml/2012/3/22/384
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