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

[Andy Whitcroft]

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

Based on the thread discussion this is the right commit.  Looks correct
as per upstream.

Acked-by: Andy Whitcroft <apw at canonical.com>

-apw