This is a note to let you know that I've just added the patch titled thunderbolt: Runtime PM activate both ends of the device link to the 5.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: thunderbolt-runtime-pm-activate-both-ends-of-the-dev.patch and it can be found in the queue-5.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 44bcbab341c0ad15567c75d76e267dd3c70dbd7f Author: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> Date: Sun Nov 14 16:07:11 2021 +0200 thunderbolt: Runtime PM activate both ends of the device link [ Upstream commit f3380cac0c0b3a6f49ab161e2a057c363962f48d ] If protocol tunnels are already up when the driver is loaded, for instance if the boot firmware implements connection manager of its own, runtime PM reference count of the consumer devices behind the tunnel might have been increased already before the device link is created but the supplier device runtime PM reference count is not. This leads to a situation where the supplier (the Thunderbolt driver) can runtime suspend even if it should not because the corresponding protocol tunnel needs to be up causing the devices to be removed from the corresponding native bus. Prevent this from happening by making both sides of the link runtime PM active briefly. The pm_runtime_put() for the consumer (PCIe root/downstream port, xHCI) then allows it to runtime suspend again but keeps the supplier runtime resumed the whole time it is runtime active. Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/thunderbolt/acpi.c b/drivers/thunderbolt/acpi.c index b5442f979b4d0..6355fdf7d71a3 100644 --- a/drivers/thunderbolt/acpi.c +++ b/drivers/thunderbolt/acpi.c @@ -7,6 +7,7 @@ */ #include <linux/acpi.h> +#include <linux/pm_runtime.h> #include "tb.h" @@ -74,8 +75,18 @@ static acpi_status tb_acpi_add_link(acpi_handle handle, u32 level, void *data, pci_pcie_type(pdev) == PCI_EXP_TYPE_DOWNSTREAM))) { const struct device_link *link; + /* + * Make them both active first to make sure the NHI does + * not runtime suspend before the consumer. The + * pm_runtime_put() below then allows the consumer to + * runtime suspend again (which then allows NHI runtime + * suspend too now that the device link is established). + */ + pm_runtime_get_sync(&pdev->dev); + link = device_link_add(&pdev->dev, &nhi->pdev->dev, DL_FLAG_AUTOREMOVE_SUPPLIER | + DL_FLAG_RPM_ACTIVE | DL_FLAG_PM_RUNTIME); if (link) { dev_dbg(&nhi->pdev->dev, "created link from %s\n", @@ -84,6 +95,8 @@ static acpi_status tb_acpi_add_link(acpi_handle handle, u32 level, void *data, dev_warn(&nhi->pdev->dev, "device link creation from %s failed\n", dev_name(&pdev->dev)); } + + pm_runtime_put(&pdev->dev); } out_put: