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Commit 84e2e577 authored by Mathias Nyman's avatar Mathias Nyman Committed by Greg Kroah-Hartman
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usb: acpi: add helper to check port lpm capability using acpi _DSM 

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@vger.kernel.org
Tested-by: default avatarRon Lee <ron.lee@intel.com>
Signed-off-by: default avatarMathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20230116142216.1141605-7-mathias.nyman@linux.intel.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 8a6e963b

drivers/usb/core/usb-acpi.c

+65 −0
Original line number Diff line number Diff line
@@ -37,6 +37,71 @@ bool usb_acpi_power_manageable(struct usb_device *hdev, int index) 
}

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

include/linux/usb.h

+3 −0
Original line number Diff line number Diff line
@@ -751,11 +751,14 @@ extern void usb_queue_reset_device(struct usb_interface *dev); 
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 */