Re: [PATCH] PCI: Enable ASPM state clearing regardless of policy

[Andrew Morton <akpm@linux-foundation.org>]

On Thu, 10 Mar 2011 11:54:16 -0700
Alex Williamson <alex.williamson@redhat.com> wrote:

> Commit 2f671e2d allowed us to clear ASPM state when the FADT
> tells us it isn't supported, but we don't put this into effect
> if the aspm_policy is set to POLICY_POWERSAVE.  Enable the
> state to be cleared regardless of policy.
> 
> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> ---
> 
>  drivers/pci/pcie/aspm.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
> index 3188cd9..eb8ac5c 100644
> --- a/drivers/pci/pcie/aspm.c
> +++ b/drivers/pci/pcie/aspm.c
> @@ -607,7 +607,7 @@ void pcie_aspm_init_link_state(struct pci_dev *pdev)
>  	 * the BIOS's expectation, we'll do so once pci_enable_device() is
>  	 * called.
>  	 */
> -	if (aspm_policy != POLICY_POWERSAVE) {
> +	if (aspm_policy != POLICY_POWERSAVE || aspm_clear_state) {
>  		pcie_config_aspm_path(link);
>  		pcie_set_clkpm(link, policy_to_clkpm_state(link));
>  	}

hm.  why.  Presumably this change has some user-observeable effect.

What is that effect, and why is it desirable? ;)