On Monday, December 06, 2010, Matthew Garrett wrote:
> We currently refuse to touch the ASPM registers if the BIOS tells us that
> ASPM isn't supported. This can cause problems if the BIOS has (for any
> reason) enabled ASPM on some devices anyway. Change the code such that we
> explicitly clear ASPM if the FADT indicates that ASPM isn't supported,
> and make sure we tidy up appropriately on device removal in order to deal
> with the hotplug case. If ASPM is disabled because the BIOS doesn't hand
> over control then we won't touch the registers.
>
> Signed-off-by: Matthew Garrett <mjg@xxxxxxxxxx>
Acked-by: Rafael J. Wysocki <rjw@xxxxxxx>
> ---
>
> Implement Rafael's suggestion to use two separate functions, and also
> ensure that we clear the clkpm bit as well as the ASPM bits.
>
> drivers/pci/pci-acpi.c | 1 +
> drivers/pci/pcie/aspm.c | 21 +++++++++++++++++----
> include/linux/pci-aspm.h | 5 ++++-
> 3 files changed, 22 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
> index 24e19c5..d7ea699 100644
> --- a/drivers/pci/pci-acpi.c
> +++ b/drivers/pci/pci-acpi.c
> @@ -399,6 +399,7 @@ static int __init acpi_pci_init(void)
>
> if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_ASPM) {
> printk(KERN_INFO"ACPI FADT declares the system doesn't support PCIe ASPM, so disable it\n");
> + pcie_clear_aspm();
> pcie_no_aspm();
> }
>
> diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
> index 7122281..8112415 100644
> --- a/drivers/pci/pcie/aspm.c
> +++ b/drivers/pci/pcie/aspm.c
> @@ -68,7 +68,7 @@ struct pcie_link_state {
> struct aspm_latency acceptable[8];
> };
>
> -static int aspm_disabled, aspm_force;
> +static int aspm_disabled, aspm_force, aspm_clear_state;
> static DEFINE_MUTEX(aspm_lock);
> static LIST_HEAD(link_list);
>
> @@ -139,7 +139,7 @@ static void pcie_set_clkpm(struct pcie_link_state *link, int enable)
> {
> /* Don't enable Clock PM if the link is not Clock PM capable */
> if (!link->clkpm_capable && enable)
> - return;
> + enable = 0;
> /* Need nothing if the specified equals to current state */
> if (link->clkpm_enabled == enable)
> return;
> @@ -498,6 +498,10 @@ static int pcie_aspm_sanity_check(struct pci_dev *pdev)
> struct pci_dev *child;
> int pos;
> u32 reg32;
> +
> + if (aspm_clear_state)
> + return -EINVAL;
> +
> /*
> * Some functions in a slot might not all be PCIe functions,
> * very strange. Disable ASPM for the whole slot
> @@ -563,12 +567,15 @@ void pcie_aspm_init_link_state(struct pci_dev *pdev)
> struct pcie_link_state *link;
> int blacklist = !!pcie_aspm_sanity_check(pdev);
>
> - if (aspm_disabled || !pci_is_pcie(pdev) || pdev->link_state)
> + if (!pci_is_pcie(pdev) || pdev->link_state)
> return;
> if (pdev->pcie_type != PCI_EXP_TYPE_ROOT_PORT &&
> pdev->pcie_type != PCI_EXP_TYPE_DOWNSTREAM)
> return;
>
> + if (aspm_disabled && !aspm_clear_state)
> + return;
> +
> /* VIA has a strange chipset, root port is under a bridge */
> if (pdev->pcie_type == PCI_EXP_TYPE_ROOT_PORT &&
> pdev->bus->self)
> @@ -641,7 +648,7 @@ void pcie_aspm_exit_link_state(struct pci_dev *pdev)
> struct pci_dev *parent = pdev->bus->self;
> struct pcie_link_state *link, *root, *parent_link;
>
> - if (aspm_disabled || !pci_is_pcie(pdev) ||
> + if ((aspm_disabled && !aspm_clear_state) || !pci_is_pcie(pdev) ||
> !parent || !parent->link_state)
> return;
> if ((parent->pcie_type != PCI_EXP_TYPE_ROOT_PORT) &&
> @@ -899,6 +906,12 @@ static int __init pcie_aspm_disable(char *str)
>
> __setup("pcie_aspm=", pcie_aspm_disable);
>
> +void pci_clear_aspm(void)
> +{
> + if (!aspm_force)
> + aspm_clear_state = 1;
> +}
> +
> void pcie_no_aspm(void)
> {
> if (!aspm_force)
> diff --git a/include/linux/pci-aspm.h b/include/linux/pci-aspm.h
> index 91ba0b3..ce68105 100644
> --- a/include/linux/pci-aspm.h
> +++ b/include/linux/pci-aspm.h
> @@ -27,6 +27,7 @@ extern void pcie_aspm_init_link_state(struct pci_dev *pdev);
> extern void pcie_aspm_exit_link_state(struct pci_dev *pdev);
> extern void pcie_aspm_pm_state_change(struct pci_dev *pdev);
> extern void pci_disable_link_state(struct pci_dev *pdev, int state);
> +extern void pcie_clear_aspm(void);
> extern void pcie_no_aspm(void);
> #else
> static inline void pcie_aspm_init_link_state(struct pci_dev *pdev)
> @@ -41,7 +42,9 @@ static inline void pcie_aspm_pm_state_change(struct pci_dev *pdev)
> static inline void pci_disable_link_state(struct pci_dev *pdev, int state)
> {
> }
> -
> +static inline void pcie_clear_aspm(void)
> +{
> +}
> static inline void pcie_no_aspm(void)
> {
> }
>
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