From: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> commit cd702d18c882d5a4ea44bbdb38edd5d5577ef640 upstream. Add a helper to evaluate ACPI usb device specific method (_DSM) provided in case the USB3 port shouldn't enter U1 and U2 link states. This _DSM was added as port specific retimer configuration may lead to exit latencies growing beyond U1/U2 exit limits, and OS needs a way to find which ports can't support U1/U2 link power management states. This _DSM is also used by windows: Link: https://docs.microsoft.com/en-us/windows-hardware/drivers/bringup/usb-device-specific-method---dsm- Some patch issues found in testing resolved by Ron Lee Cc: stable@xxxxxxxxxxxxxxx Tested-by: Ron Lee <ron.lee@xxxxxxxxx> Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20230116142216.1141605-7-mathias.nyman@xxxxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/usb/core/usb-acpi.c | 65 ++++++++++++++++++++++++++++++++++++++++++++ include/linux/usb.h | 3 ++ 2 files changed, 68 insertions(+) --- a/drivers/usb/core/usb-acpi.c +++ b/drivers/usb/core/usb-acpi.c @@ -37,6 +37,71 @@ bool usb_acpi_power_manageable(struct us } EXPORT_SYMBOL_GPL(usb_acpi_power_manageable); +#define UUID_USB_CONTROLLER_DSM "ce2ee385-00e6-48cb-9f05-2edb927c4899" +#define USB_DSM_DISABLE_U1_U2_FOR_PORT 5 + +/** + * usb_acpi_port_lpm_incapable - check if lpm should be disabled for a port. + * @hdev: USB device belonging to the usb hub + * @index: zero based port index + * + * Some USB3 ports may not support USB3 link power management U1/U2 states + * due to different retimer setup. ACPI provides _DSM method which returns 0x01 + * if U1 and U2 states should be disabled. Evaluate _DSM with: + * Arg0: UUID = ce2ee385-00e6-48cb-9f05-2edb927c4899 + * Arg1: Revision ID = 0 + * Arg2: Function Index = 5 + * Arg3: (empty) + * + * Return 1 if USB3 port is LPM incapable, negative on error, otherwise 0 + */ + +int usb_acpi_port_lpm_incapable(struct usb_device *hdev, int index) +{ + union acpi_object *obj; + acpi_handle port_handle; + int port1 = index + 1; + guid_t guid; + int ret; + + ret = guid_parse(UUID_USB_CONTROLLER_DSM, &guid); + if (ret) + return ret; + + port_handle = usb_get_hub_port_acpi_handle(hdev, port1); + if (!port_handle) { + dev_dbg(&hdev->dev, "port-%d no acpi handle\n", port1); + return -ENODEV; + } + + if (!acpi_check_dsm(port_handle, &guid, 0, + BIT(USB_DSM_DISABLE_U1_U2_FOR_PORT))) { + dev_dbg(&hdev->dev, "port-%d no _DSM function %d\n", + port1, USB_DSM_DISABLE_U1_U2_FOR_PORT); + return -ENODEV; + } + + obj = acpi_evaluate_dsm(port_handle, &guid, 0, + USB_DSM_DISABLE_U1_U2_FOR_PORT, NULL); + + if (!obj) + return -ENODEV; + + if (obj->type != ACPI_TYPE_INTEGER) { + dev_dbg(&hdev->dev, "evaluate port-%d _DSM failed\n", port1); + ACPI_FREE(obj); + return -EINVAL; + } + + if (obj->integer.value == 0x01) + ret = 1; + + ACPI_FREE(obj); + + return ret; +} +EXPORT_SYMBOL_GPL(usb_acpi_port_lpm_incapable); + /** * usb_acpi_set_power_state - control usb port's power via acpi power * resource --- a/include/linux/usb.h +++ b/include/linux/usb.h @@ -749,11 +749,14 @@ extern struct device *usb_intf_get_dma_d extern int usb_acpi_set_power_state(struct usb_device *hdev, int index, bool enable); extern bool usb_acpi_power_manageable(struct usb_device *hdev, int index); +extern int usb_acpi_port_lpm_incapable(struct usb_device *hdev, int index); #else static inline int usb_acpi_set_power_state(struct usb_device *hdev, int index, bool enable) { return 0; } static inline bool usb_acpi_power_manageable(struct usb_device *hdev, int index) { return true; } +static inline int usb_acpi_port_lpm_incapable(struct usb_device *hdev, int index) + { return 0; } #endif /* USB autosuspend and autoresume */
