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SubjectRe: [PATCH] pci: Don't enable aspm before drivers have had a chance to veto it
Reviewed-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>


(2010/06/10 5:05), Matthew Garrett wrote:
> The aspm code will currently set the configured aspm policy before drivers
> have had an opportunity to indicate that their hardware doesn't support it.
> Unfortunately, putting some hardware in L0 or L1 can result in the hardware
> no longer responding to any requests, even after aspm is disabled. It makes
> more sense to leave aspm policy at the BIOS defaults at initial setup time,
> reconfiguring it after pci_enable_device() is called. This allows the
> driver to blacklist individual devices beforehand.
>
> Signed-off-by: Matthew Garrett<mjg@redhat.com>
> ---
>
> Cleaned up slightly to remove the hacky aspm_policy changing.
>
> drivers/pci/pcie/aspm.c | 16 ++++++++++++++--
> 1 files changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
> index be53d98..7122281 100644
> --- a/drivers/pci/pcie/aspm.c
> +++ b/drivers/pci/pcie/aspm.c
> @@ -588,11 +588,23 @@ void pcie_aspm_init_link_state(struct pci_dev *pdev)
> * update through pcie_aspm_cap_init().
> */
> pcie_aspm_cap_init(link, blacklist);
> - pcie_config_aspm_path(link);
>
> /* Setup initial Clock PM state */
> pcie_clkpm_cap_init(link, blacklist);
> - pcie_set_clkpm(link, policy_to_clkpm_state(link));
> +
> + /*
> + * At this stage drivers haven't had an opportunity to change the
> + * link policy setting. Enabling ASPM on broken hardware can cripple
> + * it even before the driver has had a chance to disable ASPM, so
> + * default to a safe level right now. If we're enabling ASPM beyond
> + * the BIOS's expectation, we'll do so once pci_enable_device() is
> + * called.
> + */
> + if (aspm_policy != POLICY_POWERSAVE) {
> + pcie_config_aspm_path(link);
> + pcie_set_clkpm(link, policy_to_clkpm_state(link));
> + }
> +
> unlock:
> mutex_unlock(&aspm_lock);
> out:




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