[Oneiric PATCH] ASPM: Fix pcie devices with non-pcie children

[Tim Gardner]

On 04/02/2012 09:48 AM, Andy Whitcroft wrote:
> On Mon, Apr 02, 2012 at 09:41:24AM -0600, Tim Gardner wrote:
>> From: Matthew Garrett <mjg at redhat.com>
>>
>> BugLink: http://bugs.launchpad.net/bugs/961482
>>
>> Since 3.2.12 and 3.3, some systems are failing to boot with a BUG_ON.
>> Some other systems using the pata_jmicron driver fail to boot because no
>> disks are detected.  Passing pcie_aspm=force on the kernel command line
>> works around it.
>>
>> The cause: commit 4949be16822e ("PCI: ignore pre-1.1 ASPM quirking when
>> ASPM is disabled") changed the behaviour of pcie_aspm_sanity_check() to
>> always return 0 if aspm is disabled, in order to avoid cases where we
>> changed ASPM state on pre-PCIe 1.1 devices.
>>
>> This skipped the secondary function of pcie_aspm_sanity_check which was
>> to avoid us enabling ASPM on devices that had non-PCIe children, causing
>> trouble later on.  Move the aspm_disabled check so we continue to honour
>> that scenario.
>>
>> Addresses https://bugzilla.kernel.org/show_bug.cgi?id=42979 and
>>           http://bugs.debian.org/665420
>>
>> Reported-by: Romain Francoise <romain at orebokech.com> # kernel panic
>> Reported-by: Chris Holland <bandidoirlandes at gmail.com> # disk detection trouble
>> Signed-off-by: Matthew Garrett <mjg at redhat.com>
>> Cc: stable at vger.kernel.org
>> Tested-by: Hatem Masmoudi <hatem.masmoudi at gmail.com> # Dell Latitude E5520
>> Tested-by: janek <jan0x6c at gmail.com> # pata_jmicron with JMB362/JMB363
>> [jn: with more symptoms in log message]
>> Signed-off-by: Jonathan Nieder <jrnieder at gmail.com>
>> Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
>> (cherry picked from commit c9651e70ad0aa499814817cbf3cc1d0b806ed3a1)
>>
>> Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
>> ---
>>  drivers/pci/pcie/aspm.c |   13 ++++++++++---
>>  1 files changed, 10 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
>> index 56a6966..0ff0182 100644
>> --- a/drivers/pci/pcie/aspm.c
>> +++ b/drivers/pci/pcie/aspm.c
>> @@ -500,9 +500,6 @@ 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
>> @@ -511,6 +508,16 @@ static int pcie_aspm_sanity_check(struct pci_dev *pdev)
>>  		pos = pci_pcie_cap(child);
>>  		if (!pos)
>>  			return -EINVAL;
>> +
>> +		/*
>> +		 * If ASPM is disabled then we're not going to change
>> +		 * the BIOS state. It's safe to continue even if it's a
>> +		 * pre-1.1 device
>> +		 */
>> +
>> +		if (aspm_disabled)
>> +			continue;
>> +
>>  		/*
>>  		 * Disable ASPM for pre-1.1 PCIe device, we follow MS to use
>>  		 * RBER bit to determine if a function is 1.1 version device
> 
> Do we not need the second patch Colin proposed as well to avoid
> regressions here?
> 
> Colin?
> 
> -apw

The stable updates patch that caused the Oneiric/Precise ASPM boot
regression is "PCI: ignore pre-1.1 ASPM quirking when ASPM is disabled".
The patch to correct that regression is "ASPM: Fix pcie devices with
non-pcie children"; contained in Precise but not yet in Oneiric.

rtg
-- 
Tim Gardner tim.gardner at canonical.com