From 6ef13824e0d897858ea4510a2c61b00445922fad Mon Sep 17 00:00:00 2001 From: Lukas Wunner Date: Fri, 28 Oct 2016 10:52:06 +0200 Subject: ACPI / hotplug / PCI: Use cached copy of PCI_EXP_SLTCAP_HPC bit We cache the PCI_EXP_SLTCAP_HPC bit in pci_dev->is_hotplug_bridge on device probe, so there's no need to read it again when adding the ACPI hotplug context. Here's the call chain to prove that no ordering issue is introduced: pci_scan_child_bus [drivers/pci/probe.c] pci_scan_slot pci_scan_single_device pci_scan_device pci_setup_device set_pcie_hotplug_bridge [is_hotplug_bridge bit is set here] pci_scan_bridge pci_add_new_bus pci_alloc_child_bus pcibios_add_bus [arch/(x86|arm64|ia64)/...] acpi_pci_add_bus [drivers/pci/pci-acpi.c] acpiphp_enumerate_slots [drivers/pci/hotplug/acpiphp_glue.c] acpiphp_add_context device_is_managed_by_native_pciehp [is_hotplug_bridge bit is queried here] No functional change intended. Tested-by: Mika Westerberg Signed-off-by: Lukas Wunner Signed-off-by: Bjorn Helgaas Reviewed-by: Rafael J. Wysocki --- drivers/pci/hotplug/acpiphp_glue.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) (limited to 'drivers/pci/hotplug') diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c index a46b585fae31..b286a56e84b3 100644 --- a/drivers/pci/hotplug/acpiphp_glue.c +++ b/drivers/pci/hotplug/acpiphp_glue.c @@ -225,14 +225,11 @@ static void acpiphp_post_dock_fixup(struct acpi_device *adev) /* Check whether the PCI device is managed by native PCIe hotplug driver */ static bool device_is_managed_by_native_pciehp(struct pci_dev *pdev) { - u32 reg32; acpi_handle tmp; struct acpi_pci_root *root; /* Check whether the PCIe port supports native PCIe hotplug */ - if (pcie_capability_read_dword(pdev, PCI_EXP_SLTCAP, ®32)) - return false; - if (!(reg32 & PCI_EXP_SLTCAP_HPC)) + if (!pdev->is_hotplug_bridge) return false; /* -- cgit v1.2.3 From 437eb7bf7b28472f8b7689e166dc1dd691367121 Mon Sep 17 00:00:00 2001 From: Lukas Wunner Date: Fri, 28 Oct 2016 10:52:06 +0200 Subject: ACPI / hotplug / PCI: Make device_is_managed_by_native_pciehp() public We're about to add runtime PM of hotplug ports, but we need to restrict it to ports that are handled natively by the OS: If they're handled by the firmware (which is the case for Thunderbolt on non-Macs), things would break if the OS put the ports into D3hot behind the firmware's back. To determine if a hotplug port is handled natively, one has to walk up from the port to the root bridge and check the cached _OSC Control Field for the value of the "PCI Express Native Hot Plug control" bit. There's already a function to do that, device_is_managed_by_native_pciehp(), but it's private to drivers/pci/hotplug/acpiphp_glue.c and only compiled in if CONFIG_HOTPLUG_PCI_ACPI is enabled. Make it public and move it to drivers/pci/pci-acpi.c, so that it is available in the more general CONFIG_ACPI case. The function contains a check if the device in question is a hotplug port and returns false if it's not. The caller we're going to add doesn't need this as it only calls the function if it actually *is* a hotplug port. Move the check out of the function into the single existing caller. Rename it to pciehp_is_native() and add some kerneldoc and polish. No functional change intended. Tested-by: Mika Westerberg Signed-off-by: Lukas Wunner Signed-off-by: Bjorn Helgaas Reviewed-by: Rafael J. Wysocki --- drivers/pci/hotplug/acpiphp_glue.c | 28 +--------------------------- drivers/pci/pci-acpi.c | 24 ++++++++++++++++++++++++ include/linux/pci_hotplug.h | 2 ++ 3 files changed, 27 insertions(+), 27 deletions(-) (limited to 'drivers/pci/hotplug') diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c index b286a56e84b3..5ed2dcaa8e27 100644 --- a/drivers/pci/hotplug/acpiphp_glue.c +++ b/drivers/pci/hotplug/acpiphp_glue.c @@ -222,32 +222,6 @@ static void acpiphp_post_dock_fixup(struct acpi_device *adev) acpiphp_let_context_go(context); } -/* Check whether the PCI device is managed by native PCIe hotplug driver */ -static bool device_is_managed_by_native_pciehp(struct pci_dev *pdev) -{ - acpi_handle tmp; - struct acpi_pci_root *root; - - /* Check whether the PCIe port supports native PCIe hotplug */ - if (!pdev->is_hotplug_bridge) - return false; - - /* - * Check whether native PCIe hotplug has been enabled for - * this PCIe hierarchy. - */ - tmp = acpi_find_root_bridge_handle(pdev); - if (!tmp) - return false; - root = acpi_pci_find_root(tmp); - if (!root) - return false; - if (!(root->osc_control_set & OSC_PCI_EXPRESS_NATIVE_HP_CONTROL)) - return false; - - return true; -} - /** * acpiphp_add_context - Add ACPIPHP context to an ACPI device object. * @handle: ACPI handle of the object to add a context to. @@ -331,7 +305,7 @@ static acpi_status acpiphp_add_context(acpi_handle handle, u32 lvl, void *data, * expose slots to user space in those cases. */ if ((acpi_pci_check_ejectable(pbus, handle) || is_dock_device(adev)) - && !(pdev && device_is_managed_by_native_pciehp(pdev))) { + && !(pdev && pdev->is_hotplug_bridge && pciehp_is_native(pdev))) { unsigned long long sun; int retval; diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c index d966d47c9e80..ed3daa8e7658 100644 --- a/drivers/pci/pci-acpi.c +++ b/drivers/pci/pci-acpi.c @@ -293,6 +293,30 @@ int pci_get_hp_params(struct pci_dev *dev, struct hotplug_params *hpp) } EXPORT_SYMBOL_GPL(pci_get_hp_params); +/** + * pciehp_is_native - Check whether a hotplug port is handled by the OS + * @pdev: Hotplug port to check + * + * Walk up from @pdev to the host bridge, obtain its cached _OSC Control Field + * and return the value of the "PCI Express Native Hot Plug control" bit. + * On failure to obtain the _OSC Control Field return %false. + */ +bool pciehp_is_native(struct pci_dev *pdev) +{ + struct acpi_pci_root *root; + acpi_handle handle; + + handle = acpi_find_root_bridge_handle(pdev); + if (!handle) + return false; + + root = acpi_pci_find_root(handle); + if (!root) + return false; + + return root->osc_control_set & OSC_PCI_EXPRESS_NATIVE_HP_CONTROL; +} + /** * pci_acpi_wake_bus - Root bus wakeup notification fork function. * @work: Work item to handle. diff --git a/include/linux/pci_hotplug.h b/include/linux/pci_hotplug.h index 8c7895061121..2e855afa0212 100644 --- a/include/linux/pci_hotplug.h +++ b/include/linux/pci_hotplug.h @@ -176,6 +176,7 @@ struct hotplug_params { #ifdef CONFIG_ACPI #include int pci_get_hp_params(struct pci_dev *dev, struct hotplug_params *hpp); +bool pciehp_is_native(struct pci_dev *pdev); int acpi_get_hp_hw_control_from_firmware(struct pci_dev *dev, u32 flags); int acpi_pci_check_ejectable(struct pci_bus *pbus, acpi_handle handle); int acpi_pci_detect_ejectable(acpi_handle handle); @@ -185,5 +186,6 @@ static inline int pci_get_hp_params(struct pci_dev *dev, { return -ENODEV; } +static inline bool pciehp_is_native(struct pci_dev *pdev) { return true; } #endif #endif -- cgit v1.2.3 From 68db9bc814362e7f24371c27d12a4f34477d9356 Mon Sep 17 00:00:00 2001 From: Lukas Wunner Date: Fri, 28 Oct 2016 10:52:06 +0200 Subject: PCI: pciehp: Add runtime PM support for PCIe hotplug ports Linux 4.8 added support for runtime suspending PCIe ports to D3hot with commit 006d44e49a25 ("PCI: Add runtime PM support for PCIe ports"), but excluded hotplug ports. Those are now afforded runtime PM by the present commit. Hotplug ports require a few extra considerations: - The configuration space of the port remains accessible in D3hot, so all the functions to read or modify the Slot Status and Slot Control registers need not be modified. Even turning on slot power doesn't seem to require the port to be in D0, at least the PCIe spec doesn't say so and I confirmed that by testing with a Thunderbolt controller. - However D0 is required to access devices on the secondary bus. This happens in pciehp_check_link_status() and pciehp_configure_device() (both called from board_added()) and in pciehp_unconfigure_device() (called from remove_board()), so acquire a runtime PM ref for their invocation. - The hotplug port stays active as long as it has active children. If all hotplugged devices below the port runtime suspend, the port is allowed to runtime suspend as well. Plug and unplug detection continues to work in D3hot. - Hotplug interrupts are delivered in-band, so while the hotplug port itself is allowed to go to D3hot, its parent ports must stay in D0 for interrupts to come through. Add a corresponding restriction to pci_dev_check_d3cold(). - Runtime PM may only be allowed if the hotplug port is handled natively by the OS. On ACPI systems, the port may alternatively be handled by the firmware and things break if the OS puts the port into D3 behind the firmware's back: E.g. Thunderbolt hotplug ports on non-Macs are handled by Intel's firmware in System Management Mode and the firmware is known to access devices on the port's secondary bus without checking first if the port is in D0: https://bugzilla.kernel.org/show_bug.cgi?id=53811 Signed-off-by: Lukas Wunner Signed-off-by: Bjorn Helgaas Reviewed-by: Rafael J. Wysocki CC: Mika Westerberg --- drivers/pci/hotplug/pciehp_ctrl.c | 6 ++++++ drivers/pci/pci.c | 12 ++++++------ 2 files changed, 12 insertions(+), 6 deletions(-) (limited to 'drivers/pci/hotplug') diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c index efe69e879455..ffd3fe6646c2 100644 --- a/drivers/pci/hotplug/pciehp_ctrl.c +++ b/drivers/pci/hotplug/pciehp_ctrl.c @@ -31,6 +31,7 @@ #include #include #include +#include #include #include "../pci.h" #include "pciehp.h" @@ -98,6 +99,7 @@ static int board_added(struct slot *p_slot) pciehp_green_led_blink(p_slot); /* Check link training status */ + pm_runtime_get_sync(&ctrl->pcie->port->dev); retval = pciehp_check_link_status(ctrl); if (retval) { ctrl_err(ctrl, "Failed to check link status\n"); @@ -118,12 +120,14 @@ static int board_added(struct slot *p_slot) if (retval != -EEXIST) goto err_exit; } + pm_runtime_put(&ctrl->pcie->port->dev); pciehp_green_led_on(p_slot); pciehp_set_attention_status(p_slot, 0); return 0; err_exit: + pm_runtime_put(&ctrl->pcie->port->dev); set_slot_off(ctrl, p_slot); return retval; } @@ -137,7 +141,9 @@ static int remove_board(struct slot *p_slot) int retval; struct controller *ctrl = p_slot->ctrl; + pm_runtime_get_sync(&ctrl->pcie->port->dev); retval = pciehp_unconfigure_device(p_slot); + pm_runtime_put(&ctrl->pcie->port->dev); if (retval) return retval; diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index d86351a2fe6e..1eb622cc8645 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -2245,13 +2245,10 @@ bool pci_bridge_d3_possible(struct pci_dev *bridge) return false; /* - * Hotplug interrupts cannot be delivered if the link is down, - * so parents of a hotplug port must stay awake. In addition, - * hotplug ports handled by firmware in System Management Mode + * Hotplug ports handled by firmware in System Management Mode * may not be put into D3 by the OS (Thunderbolt on non-Macs). - * For simplicity, disallow in general for now. */ - if (bridge->is_hotplug_bridge) + if (bridge->is_hotplug_bridge && !pciehp_is_native(bridge)) return false; if (pci_bridge_d3_force) @@ -2283,7 +2280,10 @@ static int pci_dev_check_d3cold(struct pci_dev *dev, void *data) !pci_pme_capable(dev, PCI_D3cold)) || /* If it is a bridge it must be allowed to go to D3. */ - !pci_power_manageable(dev)) + !pci_power_manageable(dev) || + + /* Hotplug interrupts cannot be delivered if the link is down. */ + dev->is_hotplug_bridge) *d3cold_ok = false; -- cgit v1.2.3