On Mon, Feb 28, 2022 at 08:19:41PM -0800, David E. Box wrote:
> From: Michael Bottini <michael.a.bottini@xxxxxxxxxxxxxxx>
>
> Add pci_enable_default_link_state() to allow devices to change the default
> BIOS configured states. Clears the BIOS default settings then sets the new
> states and reconfigures the link under the semaphore. Also add
> PCIE_LINK_STATE_ALL macro for convenience for callers that want to enable
> all link states.
>
> Signed-off-by: Michael Bottini <michael.a.bottini@xxxxxxxxxxxxxxx>
> Signed-off-by: David E. Box <david.e.box@xxxxxxxxxxxxxxx>
With minor changes below,
Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> + * pci_enable_default_link_state - Clears and sets the default device link state
> + * so that the link may be allowed to enter the specified states. Note that
> + * if the BIOS didn't grant ASPM control to the OS, this does nothing because
> + * we can't touch the LNKCTL register. Also note that this does not enable
> + * states disabled by pci_disable_link_state(). Returns 0 or a negative errno.
"Clear and set" to match imperative mood of similar comments.
Similarly "Return 0 or ...".
> + *
> + * @pdev: PCI device
> + * @state: Mask of ASPM link states to enable
> + */
> +int pci_enable_default_link_state(struct pci_dev *pdev, int state)
I think "pci_enable_link_state()" would be a better name since
"default" isn't relevant to the caller and it would be more parallel
with pci_disable_link_state().
> +{
> + struct pcie_link_state *link = pcie_aspm_get_link(pdev);
> +
> + if (!link)
> + return -EINVAL;
> + /*
> + * A driver requested that ASPM be enabled on this device, but
> + * if we don't have permission to manage ASPM (e.g., on ACPI
> + * systems we have to observe the FADT ACPI_FADT_NO_ASPM bit and
> + * the _OSC method), we can't honor that request.
> + */
> + if (aspm_disabled) {
> + pci_warn(pdev, "can't override BIOS ASPM; OS doesn't have ASPM control\n");
> + return -EPERM;
> + }
> +
> + down_read(&pci_bus_sem);
> + mutex_lock(&aspm_lock);
> + link->aspm_default = 0;
> + if (state & PCIE_LINK_STATE_L0S)
> + link->aspm_default |= ASPM_STATE_L0S;
> + if (state & PCIE_LINK_STATE_L1)
> + /* L1 PM substates require L1 */
> + link->aspm_default |= ASPM_STATE_L1 | ASPM_STATE_L1SS;
> + if (state & PCIE_LINK_STATE_L1_1)
> + link->aspm_default |= ASPM_STATE_L1_1;
> + if (state & PCIE_LINK_STATE_L1_2)
> + link->aspm_default |= ASPM_STATE_L1_2;
> + if (state & PCIE_LINK_STATE_L1_1_PCIPM)
> + link->aspm_default |= ASPM_STATE_L1_1_PCIPM;
> + if (state & PCIE_LINK_STATE_L1_2_PCIPM)
> + link->aspm_default |= ASPM_STATE_L1_2_PCIPM;
> + pcie_config_aspm_link(link, policy_to_aspm_state(link));
> +
> + link->clkpm_default = (state & PCIE_LINK_STATE_CLKPM) ? 1 : 0;
> + pcie_set_clkpm(link, policy_to_clkpm_state(link));
> + mutex_unlock(&aspm_lock);
> + up_read(&pci_bus_sem);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(pci_enable_default_link_state);
> +
> static int pcie_aspm_set_policy(const char *val,
> const struct kernel_param *kp)
> {
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 8253a5413d7c..fd710afe0209 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1641,10 +1641,15 @@ extern bool pcie_ports_native;
> #define PCIE_LINK_STATE_L1_2 BIT(4)
> #define PCIE_LINK_STATE_L1_1_PCIPM BIT(5)
> #define PCIE_LINK_STATE_L1_2_PCIPM BIT(6)
> +#define PCIE_LINK_STATE_ALL (PCIE_LINK_STATE_L0S | PCIE_LINK_STATE_L1 |\
> + PCIE_LINK_STATE_CLKPM | PCIE_LINK_STATE_L1_1 |\
> + PCIE_LINK_STATE_L1_2 | PCIE_LINK_STATE_L1_1_PCIPM |\
> + PCIE_LINK_STATE_L1_2_PCIPM)
>
> #ifdef CONFIG_PCIEASPM
> int pci_disable_link_state(struct pci_dev *pdev, int state);
> int pci_disable_link_state_locked(struct pci_dev *pdev, int state);
> +int pci_enable_default_link_state(struct pci_dev *pdev, int state);
> void pcie_no_aspm(void);
> bool pcie_aspm_support_enabled(void);
> bool pcie_aspm_enabled(struct pci_dev *pdev);
> @@ -1653,6 +1658,8 @@ static inline int pci_disable_link_state(struct pci_dev *pdev, int state)
> { return 0; }
> static inline int pci_disable_link_state_locked(struct pci_dev *pdev, int state)
> { return 0; }
> +static inline int pci_enable_default_link_state(struct pci_dev *pdev, int state)
> +{ return 0; }
> static inline void pcie_no_aspm(void) { }
> static inline bool pcie_aspm_support_enabled(void) { return false; }
> static inline bool pcie_aspm_enabled(struct pci_dev *pdev) { return false; }
> --
> 2.25.1
>
