> -----Original Message-----
> From: Wyborny, Carolyn
> Sent: Thursday, August 01, 2013 7:56 AM
> To: 'Pavel Machek'
> Cc: Bjorn Helgaas; Greg KH; kernel list; Joe Lawrence; Myron Stowe; Kirsher,
> Jeffrey T; Brandeburg, Jesse; Allan, Bruce W; Skidmore, Donald C; Rose, Gregory
> V; Waskiewicz Jr, Peter P; Duyck, Alexander H; Ronciak, John; Dave, Tushar N;
> e1000-devel@lists.sourceforge.net
> Subject: RE: /sys/module/pcie_aspm/parameters/policy not writable?
> 
> [..]
> > If there's patch, I'll gladly try it :-). Thanks,
> >
> 								Pavel
> Thanks Pavel,

Minor fix.  Missed a bracket removal  Please use this  for your testing instead.

Thanks,

Carolyn
> 
> It ended up taking more time than I thought.  The checking of whether ASPM is
> really enabled or not is, unfortunately, not as straightforward as I thought
> initially, so we ended up rewriting the function a bit.  In this patch we try to use
> the pci_disable_link_state_locked() call, but if it fails, we then write to pci config
> space of the device to disable it.
> 
> Please let me know if this actually disables the ASPM for your 82574 parts or
> not.  We can still continue the discussion on whether this is the best approach or
> not, or what else could be done.
> 
> This patch attempts to work around a problem found with some systems where
> the call to pci_diable_link_state_locked() fails.  As a result, ASPM is not, in fact,
> disabled.  Changing disable aspm code to check if state actually is disabled after
> the call and, if not, try another way to disable it.
> 
> Signed-off-by: Carolyn Wyborny <carolyn.wyborny@intel.com>
> ---
> 
>  drivers/net/ethernet/intel/e1000e/netdev.c |   86 ++++++++++++++++++++------
> --
>  1 files changed, 60 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c
> b/drivers/net/ethernet/intel/e1000e/netdev.c
> index e6d2c0f..bc3025b 100644
> --- a/drivers/net/ethernet/intel/e1000e/netdev.c
> +++ b/drivers/net/ethernet/intel/e1000e/netdev.c
> @@ -64,8 +64,6 @@ static int debug = -1;  module_param(debug, int, 0);
> MODULE_PARM_DESC(debug, "Debug level (0=none,...,16=all)");
> 
> -static void e1000e_disable_aspm(struct pci_dev *pdev, u16 state);
> -
>  static const struct e1000_info *e1000_info_tbl[] = {
>  	[board_82571]		= &e1000_82571_info,
>  	[board_82572]		= &e1000_82572_info,
> @@ -6019,38 +6017,74 @@ static int __e1000_shutdown(struct pci_dev *pdev,
> bool runtime)
>  	return 0;
>  }
> 
> -#ifdef CONFIG_PCIEASPM
> -static void __e1000e_disable_aspm(struct pci_dev *pdev, u16 state)
> +/**
> + * e1000e_disable_aspm - Disable ASPM states
> + * @pdev: pointer to PCI device struct
> + * @state: bit-mask of ASPM states to disable
> + *
> + * Some devices *must* have certain ASPM states disabled per hardware
> errata.
> + **/
> +static void e1000e_disable_aspm(struct pci_dev *pdev, u16 state)
>  {
> +	struct pci_dev *parent = pdev->bus->self;
> +	u16 aspm_dis_mask = 0;
> +	u16 pdev_aspmc, parent_aspmc;
> +
> +	switch (state) {
> +	case PCIE_LINK_STATE_L0S:
> +	case PCIE_LINK_STATE_L0S + PCIE_LINK_STATE_L1:
> +		aspm_dis_mask |= PCI_EXP_LNKCTL_ASPM_L0S;
> +		/* fall-through - can't have L1 without L0s */
> +	case PCIE_LINK_STATE_L1:
> +		aspm_dis_mask |= PCI_EXP_LNKCTL_ASPM_L1;
> +		break;
> +	default:
> +		return;
> +	}
> +
> +	pcie_capability_read_word(pdev, PCI_EXP_LNKCTL, &pdev_aspmc);
> +	pdev_aspmc &= PCI_EXP_LNKCTL_ASPMC;
> +
> +	if (parent) {
> +		pcie_capability_read_word(parent, PCI_EXP_LNKCTL,
> +					  &parent_aspmc);
> +		parent_aspmc &= PCI_EXP_LNKCTL_ASPMC;
> +	}
> +
> +	/* Nothing to do if the ASPM states to be disabled already are */
> +	if (!(pdev_aspmc & aspm_dis_mask) &&
> +	    (!parent || !(parent_aspmc & aspm_dis_mask)))
> +		return;
> +
> +	dev_info(&pdev->dev, "Disabling ASPM %s %s\n",
> +		 (aspm_dis_mask & pdev_aspmc &
> PCI_EXP_LNKCTL_ASPM_L0S) ?
> +		 "L0s" : "",
> +		 (aspm_dis_mask & pdev_aspmc & PCI_EXP_LNKCTL_ASPM_L1)
> ?
> +		 "L1" : "");
> +
> +#ifdef CONFIG_PCIEASPM
>  	pci_disable_link_state_locked(pdev, state); -} -#else -static void
> __e1000e_disable_aspm(struct pci_dev *pdev, u16 state) -{
> -	u16 aspm_ctl = 0;
> 
> -	if (state & PCIE_LINK_STATE_L0S)
> -		aspm_ctl |= PCI_EXP_LNKCTL_ASPM_L0S;
> -	if (state & PCIE_LINK_STATE_L1)
> -		aspm_ctl |= PCI_EXP_LNKCTL_ASPM_L1;
> +	/* Double-check ASPM control.  If not disabled by the above, the
> +	 * BIOS is preventing that from happening (or CONFIG_PCIEASPM is
> +	 * not enabled); override by writing PCI config space directly.
> +	 */
> +	pcie_capability_read_word(pdev, PCI_EXP_LNKCTL, &pdev_aspmc);
> +	pdev_aspmc &= PCI_EXP_LNKCTL_ASPMC;
> +
> +	if (!(aspm_dis_mask & pdev_aspmc))
> +		return;
> +#endif
> 
>  	/* Both device and parent should have the same ASPM setting.
>  	 * Disable ASPM in downstream component first and then upstream.
>  	 */
> -	pcie_capability_clear_word(pdev, PCI_EXP_LNKCTL, aspm_ctl);
> -
> -	if (pdev->bus->self)
> -		pcie_capability_clear_word(pdev->bus->self, PCI_EXP_LNKCTL,
> -					   aspm_ctl);
> -}
> -#endif
> -static void e1000e_disable_aspm(struct pci_dev *pdev, u16 state) -{
> -	dev_info(&pdev->dev, "Disabling ASPM %s %s\n",
> -		 (state & PCIE_LINK_STATE_L0S) ? "L0s" : "",
> -		 (state & PCIE_LINK_STATE_L1) ? "L1" : "");
> +	pcie_capability_clear_word(pdev, PCI_EXP_LNKCTL, aspm_dis_mask);
> 
> -	__e1000e_disable_aspm(pdev, state);
> +	if (parent)
> +		pcie_capability_clear_word(parent, PCI_EXP_LNKCTL,
> +					   aspm_dis_mask);
>  }
> 
>  #ifdef CONFIG_PM