* [PATCH v13 1/4] usb: xhci-plat: separate dev_pm_ops for each pm_event
2025-05-28 9:04 [PATCH v13 0/4] Support system sleep with offloaded usb transfers Guan-Yu Lin
@ 2025-05-28 9:04 ` Guan-Yu Lin
2025-05-28 9:04 ` [PATCH v13 2/4] usb: add apis for offload usage tracking Guan-Yu Lin
` (2 subsequent siblings)
3 siblings, 0 replies; 7+ messages in thread
From: Guan-Yu Lin @ 2025-05-28 9:04 UTC (permalink / raw)
To: gregkh, mathias.nyman, gargaditya08, kekrby, jeff.johnson,
quic_zijuhu, andriy.shevchenko, ben, broonie, quic_wcheng,
krzysztof.kozlowski
Cc: linux-usb, linux-kernel, Guan-Yu Lin
Separate dev_pm_ops for different power events such as suspend, thaw,
and hibernation. This is crucial when xhci-plat driver needs to adapt
its behavior based on different power state changes.
Signed-off-by: Guan-Yu Lin <guanyulin@google.com>
---
drivers/usb/host/xhci-plat.c | 23 +++++++++++++++++++----
1 file changed, 19 insertions(+), 4 deletions(-)
diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
index 6dab142e7278..9843d3ad5cf4 100644
--- a/drivers/usb/host/xhci-plat.c
+++ b/drivers/usb/host/xhci-plat.c
@@ -453,7 +453,7 @@ void xhci_plat_remove(struct platform_device *dev)
}
EXPORT_SYMBOL_GPL(xhci_plat_remove);
-static int xhci_plat_suspend(struct device *dev)
+static int xhci_plat_suspend_common(struct device *dev)
{
struct usb_hcd *hcd = dev_get_drvdata(dev);
struct xhci_hcd *xhci = hcd_to_xhci(hcd);
@@ -481,6 +481,16 @@ static int xhci_plat_suspend(struct device *dev)
return 0;
}
+static int xhci_plat_suspend(struct device *dev)
+{
+ return xhci_plat_suspend_common(dev);
+}
+
+static int xhci_plat_freeze(struct device *dev)
+{
+ return xhci_plat_suspend_common(dev);
+}
+
static int xhci_plat_resume_common(struct device *dev, bool power_lost)
{
struct usb_hcd *hcd = dev_get_drvdata(dev);
@@ -528,6 +538,11 @@ static int xhci_plat_resume(struct device *dev)
return xhci_plat_resume_common(dev, false);
}
+static int xhci_plat_thaw(struct device *dev)
+{
+ return xhci_plat_resume_common(dev, false);
+}
+
static int xhci_plat_restore(struct device *dev)
{
return xhci_plat_resume_common(dev, true);
@@ -557,9 +572,9 @@ static int __maybe_unused xhci_plat_runtime_resume(struct device *dev)
const struct dev_pm_ops xhci_plat_pm_ops = {
.suspend = pm_sleep_ptr(xhci_plat_suspend),
.resume = pm_sleep_ptr(xhci_plat_resume),
- .freeze = pm_sleep_ptr(xhci_plat_suspend),
- .thaw = pm_sleep_ptr(xhci_plat_resume),
- .poweroff = pm_sleep_ptr(xhci_plat_suspend),
+ .freeze = pm_sleep_ptr(xhci_plat_freeze),
+ .thaw = pm_sleep_ptr(xhci_plat_thaw),
+ .poweroff = pm_sleep_ptr(xhci_plat_freeze),
.restore = pm_sleep_ptr(xhci_plat_restore),
SET_RUNTIME_PM_OPS(xhci_plat_runtime_suspend,
--
2.49.0.1164.gab81da1b16-goog
^ permalink raw reply related [flat|nested] 7+ messages in thread* [PATCH v13 2/4] usb: add apis for offload usage tracking
2025-05-28 9:04 [PATCH v13 0/4] Support system sleep with offloaded usb transfers Guan-Yu Lin
2025-05-28 9:04 ` [PATCH v13 1/4] usb: xhci-plat: separate dev_pm_ops for each pm_event Guan-Yu Lin
@ 2025-05-28 9:04 ` Guan-Yu Lin
2025-05-28 9:14 ` Greg KH
2025-05-28 9:04 ` [PATCH v13 3/4] xhci: sideband: add api to trace sideband usage Guan-Yu Lin
2025-05-28 9:04 ` [PATCH v13 4/4] usb: host: enable USB offload during system sleep Guan-Yu Lin
3 siblings, 1 reply; 7+ messages in thread
From: Guan-Yu Lin @ 2025-05-28 9:04 UTC (permalink / raw)
To: gregkh, mathias.nyman, gargaditya08, kekrby, jeff.johnson,
quic_zijuhu, andriy.shevchenko, ben, broonie, quic_wcheng,
krzysztof.kozlowski
Cc: linux-usb, linux-kernel, Guan-Yu Lin
Introduce offload_usage and corresponding apis to track offload usage
on each USB device. Offload denotes that there is another co-processor
accessing the USB device via the same USB host controller. To optimize
power usage, it's essential to monitor whether the USB device is
actively used by other co-processor. This information is vital when
determining if a USB device can be safely suspended during system power
state transitions.
Signed-off-by: Guan-Yu Lin <guanyulin@google.com>
---
drivers/usb/core/driver.c | 125 ++++++++++++++++++++++++++++++++++++++
drivers/usb/core/usb.c | 1 +
drivers/usb/host/Kconfig | 11 ++++
include/linux/usb.h | 18 ++++++
4 files changed, 155 insertions(+)
diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 460d4dde5994..0690619454fe 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -2036,6 +2036,131 @@ int usb_disable_usb2_hardware_lpm(struct usb_device *udev)
#endif /* CONFIG_PM */
+#if IS_ENABLED(CONFIG_USB_XHCI_SIDEBAND_SUSPEND)
+
+/**
+ * usb_offload_get - increment the offload_usage of a USB device
+ * @udev: the USB device to increment its offload_usage
+ *
+ * Incrementing the offload_usage of a usb_device indicates that offload is
+ * enabled on this usb_device; that is, another entity is actively handling USB
+ * transfers. This information allows the USB driver to adjust its power
+ * management policy based on offload activity.
+ *
+ * Return: 0 on success. A negative error code otherwise.
+ */
+int usb_offload_get(struct usb_device *udev)
+{
+ int ret;
+
+ usb_lock_device(udev);
+ if (udev->state == USB_STATE_NOTATTACHED) {
+ ret = -ENODEV;
+ goto unlock_device;
+ } else if (udev->state == USB_STATE_SUSPENDED ||
+ udev->offload_at_suspend) {
+ ret = -EBUSY;
+ goto unlock_device;
+ }
+
+ /*
+ * offload_usage could only be modified when the device is active, since
+ * it will alter the suspend flow of the device.
+ */
+ ret = usb_autoresume_device(udev);
+
+ if (ret < 0)
+ goto unlock_device;
+
+ udev->offload_usage++;
+ usb_autosuspend_device(udev);
+
+unlock_device:
+ usb_unlock_device(udev);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(usb_offload_get);
+
+/**
+ * usb_offload_put - drop the offload_usage of a USB device
+ * @udev: the USB device to drop its offload_usage
+ *
+ * The inverse operation of usb_offload_get, which drops the offload_usage of
+ * a USB device. This information allows the USB driver to adjust its power
+ * management policy based on offload activity.
+ *
+ * Return: 0 on success. A negative error code otherwise.
+ */
+int usb_offload_put(struct usb_device *udev)
+{
+ int ret;
+
+ usb_lock_device(udev);
+ if (udev->state == USB_STATE_NOTATTACHED) {
+ ret = -ENODEV;
+ goto unlock_device;
+ } else if (udev->state == USB_STATE_SUSPENDED ||
+ udev->offload_at_suspend) {
+ ret = -EBUSY;
+ goto unlock_device;
+ }
+
+ /*
+ * offload_usage could only be modified when the device is active, since
+ * it will alter the suspend flow of the device.
+ */
+ ret = usb_autoresume_device(udev);
+
+ if (ret < 0)
+ goto unlock_device;
+
+ /* Drop the count when it wasn't 0, ignore the operation otherwise. */
+ if (udev->offload_usage)
+ udev->offload_usage--;
+ usb_autosuspend_device(udev);
+
+unlock_device:
+ usb_unlock_device(udev);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(usb_offload_put);
+
+/**
+ * usb_offload_check - check offload activities on a USB device
+ * @udev: the USB device to check its offload activity.
+ *
+ * Check if there are any offload activity on the USB device right now. This
+ * information could be used for power management or other forms of resource
+ * management.
+ *
+ * The caller must hold @udev's device lock. In addition, the caller should
+ * ensure downstream usb devices are all either suspended or marked as
+ * "offload_at_suspend" to ensure the correctness of the return value.
+ *
+ * Returns true on any offload activity, false otherwise.
+ */
+bool usb_offload_check(struct usb_device *udev)
+{
+ struct usb_device *child;
+ bool active;
+ int port1;
+
+ usb_hub_for_each_child(udev, port1, child) {
+ usb_lock_device(child);
+ active = usb_offload_check(child);
+ usb_unlock_device(child);
+ if (active)
+ return true;
+ }
+
+ return !!udev->offload_usage;
+}
+EXPORT_SYMBOL_GPL(usb_offload_check);
+
+#endif /* IS_ENABLED(CONFIG_USB_XHCI_SIDEBAND_SUSPEND) */
+
const struct bus_type usb_bus_type = {
.name = "usb",
.match = usb_device_match,
diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index 118fa4c93a79..43efd9d939c0 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -670,6 +670,7 @@ struct usb_device *usb_alloc_dev(struct usb_device *parent,
set_dev_node(&dev->dev, dev_to_node(bus->sysdev));
dev->state = USB_STATE_ATTACHED;
dev->lpm_disable_count = 1;
+ dev->offload_usage = 0;
atomic_set(&dev->urbnum, 0);
INIT_LIST_HEAD(&dev->ep0.urb_list);
diff --git a/drivers/usb/host/Kconfig b/drivers/usb/host/Kconfig
index 109100cc77a3..49b9cdc11298 100644
--- a/drivers/usb/host/Kconfig
+++ b/drivers/usb/host/Kconfig
@@ -113,6 +113,17 @@ config USB_XHCI_SIDEBAND
xHCI USB endpoints directly, allowing CPU to sleep while playing
audio.
+config USB_XHCI_SIDEBAND_SUSPEND
+ bool "xHCI support for sideband during system suspend"
+ depends on USB_XHCI_SIDEBAND
+ depends on USB_XHCI_PLATFORM
+ depends on SUSPEND
+ help
+ Say 'Y' to enable the support for the xHCI sideband capability
+ after system suspended. In addition to USB_XHCI_SIDEBAND, this
+ config allows endpoints and interrupters associated with the
+ sideband function when system is suspended.
+
config USB_XHCI_TEGRA
tristate "xHCI support for NVIDIA Tegra SoCs"
depends on PHY_TEGRA_XUSB
diff --git a/include/linux/usb.h b/include/linux/usb.h
index 1b2545b4363b..f5bca317fa4c 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -635,6 +635,8 @@ struct usb3_lpm_parameters {
* @do_remote_wakeup: remote wakeup should be enabled
* @reset_resume: needs reset instead of resume
* @port_is_suspended: the upstream port is suspended (L2 or U3)
+ * @offload_at_suspend: offload activities during suspend is enabled.
+ * @offload_usage: number of offload activities happening on this usb device.
* @slot_id: Slot ID assigned by xHCI
* @l1_params: best effor service latency for USB2 L1 LPM state, and L1 timeout.
* @u1_params: exit latencies for USB3 U1 LPM state, and hub-initiated timeout.
@@ -723,6 +725,8 @@ struct usb_device {
unsigned do_remote_wakeup:1;
unsigned reset_resume:1;
unsigned port_is_suspended:1;
+ unsigned offload_at_suspend:1;
+ int offload_usage;
enum usb_link_tunnel_mode tunnel_mode;
int slot_id;
@@ -839,6 +843,20 @@ static inline void usb_mark_last_busy(struct usb_device *udev)
{ }
#endif
+#if IS_ENABLED(CONFIG_USB_XHCI_SIDEBAND_SUSPEND)
+int usb_offload_get(struct usb_device *udev);
+int usb_offload_put(struct usb_device *udev);
+bool usb_offload_check(struct usb_device *udev);
+#else
+
+static inline int usb_offload_get(struct usb_device *udev)
+{ return 0; }
+static inline int usb_offload_put(struct usb_device *udev)
+{ return 0; }
+static inline bool usb_offload_check(struct usb_device *udev)
+{ return false; }
+#endif
+
extern int usb_disable_lpm(struct usb_device *udev);
extern void usb_enable_lpm(struct usb_device *udev);
/* Same as above, but these functions lock/unlock the bandwidth_mutex. */
--
2.49.0.1164.gab81da1b16-goog
^ permalink raw reply related [flat|nested] 7+ messages in thread* Re: [PATCH v13 2/4] usb: add apis for offload usage tracking
2025-05-28 9:04 ` [PATCH v13 2/4] usb: add apis for offload usage tracking Guan-Yu Lin
@ 2025-05-28 9:14 ` Greg KH
2025-06-03 8:46 ` Guan-Yu Lin
0 siblings, 1 reply; 7+ messages in thread
From: Greg KH @ 2025-05-28 9:14 UTC (permalink / raw)
To: Guan-Yu Lin
Cc: mathias.nyman, gargaditya08, kekrby, jeff.johnson, quic_zijuhu,
andriy.shevchenko, ben, broonie, quic_wcheng, krzysztof.kozlowski,
linux-usb, linux-kernel
On Wed, May 28, 2025 at 09:04:07AM +0000, Guan-Yu Lin wrote:
> Introduce offload_usage and corresponding apis to track offload usage
> on each USB device. Offload denotes that there is another co-processor
> accessing the USB device via the same USB host controller. To optimize
> power usage, it's essential to monitor whether the USB device is
> actively used by other co-processor. This information is vital when
> determining if a USB device can be safely suspended during system power
> state transitions.
>
> Signed-off-by: Guan-Yu Lin <guanyulin@google.com>
> ---
> drivers/usb/core/driver.c | 125 ++++++++++++++++++++++++++++++++++++++
> drivers/usb/core/usb.c | 1 +
> drivers/usb/host/Kconfig | 11 ++++
> include/linux/usb.h | 18 ++++++
> 4 files changed, 155 insertions(+)
>
> diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
> index 460d4dde5994..0690619454fe 100644
> --- a/drivers/usb/core/driver.c
> +++ b/drivers/usb/core/driver.c
> @@ -2036,6 +2036,131 @@ int usb_disable_usb2_hardware_lpm(struct usb_device *udev)
>
> #endif /* CONFIG_PM */
>
> +#if IS_ENABLED(CONFIG_USB_XHCI_SIDEBAND_SUSPEND)
ifdef in .c files are messy and hard to maintain.
Also, why is an xhci-specific option enabling/disabling core USB
functions like this? Shouldn't it be a generic USB config option name
instead?
> +
> +/**
> + * usb_offload_get - increment the offload_usage of a USB device
> + * @udev: the USB device to increment its offload_usage
> + *
> + * Incrementing the offload_usage of a usb_device indicates that offload is
> + * enabled on this usb_device; that is, another entity is actively handling USB
> + * transfers. This information allows the USB driver to adjust its power
> + * management policy based on offload activity.
> + *
> + * Return: 0 on success. A negative error code otherwise.
> + */
> +int usb_offload_get(struct usb_device *udev)
> +{
> + int ret;
> +
> + usb_lock_device(udev);
> + if (udev->state == USB_STATE_NOTATTACHED) {
> + ret = -ENODEV;
> + goto unlock_device;
Shouldn't we using the guard logic here instead? That would make all of
this look much simpler and easier to maintain over time.
> + } else if (udev->state == USB_STATE_SUSPENDED ||
> + udev->offload_at_suspend) {
> + ret = -EBUSY;
> + goto unlock_device;
> + }
> +
> + /*
> + * offload_usage could only be modified when the device is active, since
> + * it will alter the suspend flow of the device.
> + */
> + ret = usb_autoresume_device(udev);
> +
> + if (ret < 0)
Why the blank line?
> + goto unlock_device;
> +
> + udev->offload_usage++;
> + usb_autosuspend_device(udev);
> +
> +unlock_device:
> + usb_unlock_device(udev);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(usb_offload_get);
> +
> +/**
> + * usb_offload_put - drop the offload_usage of a USB device
> + * @udev: the USB device to drop its offload_usage
> + *
> + * The inverse operation of usb_offload_get, which drops the offload_usage of
> + * a USB device. This information allows the USB driver to adjust its power
> + * management policy based on offload activity.
> + *
> + * Return: 0 on success. A negative error code otherwise.
> + */
> +int usb_offload_put(struct usb_device *udev)
> +{
> + int ret;
> +
> + usb_lock_device(udev);
> + if (udev->state == USB_STATE_NOTATTACHED) {
> + ret = -ENODEV;
> + goto unlock_device;
> + } else if (udev->state == USB_STATE_SUSPENDED ||
> + udev->offload_at_suspend) {
> + ret = -EBUSY;
> + goto unlock_device;
> + }
> +
> + /*
> + * offload_usage could only be modified when the device is active, since
> + * it will alter the suspend flow of the device.
> + */
> + ret = usb_autoresume_device(udev);
> +
> + if (ret < 0)
> + goto unlock_device;
> +
> + /* Drop the count when it wasn't 0, ignore the operation otherwise. */
> + if (udev->offload_usage)
> + udev->offload_usage--;
> + usb_autosuspend_device(udev);
> +
> +unlock_device:
> + usb_unlock_device(udev);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(usb_offload_put);
> +
> +/**
> + * usb_offload_check - check offload activities on a USB device
> + * @udev: the USB device to check its offload activity.
> + *
> + * Check if there are any offload activity on the USB device right now. This
> + * information could be used for power management or other forms of resource
> + * management.
> + *
> + * The caller must hold @udev's device lock. In addition, the caller should
> + * ensure downstream usb devices are all either suspended or marked as
> + * "offload_at_suspend" to ensure the correctness of the return value.
> + *
> + * Returns true on any offload activity, false otherwise.
> + */
> +bool usb_offload_check(struct usb_device *udev)
> +{
> + struct usb_device *child;
> + bool active;
> + int port1;
> +
> + usb_hub_for_each_child(udev, port1, child) {
> + usb_lock_device(child);
> + active = usb_offload_check(child);
> + usb_unlock_device(child);
> + if (active)
> + return true;
> + }
> +
> + return !!udev->offload_usage;
I think you forgot to mark this function as requiring that the lock be
held, right? Just documenting it isn't going to be simple to notice or
maintain over time...
thanks,
greg k-h
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH v13 2/4] usb: add apis for offload usage tracking
2025-05-28 9:14 ` Greg KH
@ 2025-06-03 8:46 ` Guan-Yu Lin
0 siblings, 0 replies; 7+ messages in thread
From: Guan-Yu Lin @ 2025-06-03 8:46 UTC (permalink / raw)
To: Greg KH
Cc: mathias.nyman, gargaditya08, kekrby, jeff.johnson, quic_zijuhu,
andriy.shevchenko, ben, broonie, quic_wcheng, krzysztof.kozlowski,
linux-usb, linux-kernel
On Wed, May 28, 2025 at 5:16 PM Greg KH <gregkh@linuxfoundation.org> wrote:
>
> On Wed, May 28, 2025 at 09:04:07AM +0000, Guan-Yu Lin wrote:
> > @@ -2036,6 +2036,131 @@ int usb_disable_usb2_hardware_lpm(struct usb_device *udev)
> >
> > #endif /* CONFIG_PM */
> >
> > +#if IS_ENABLED(CONFIG_USB_XHCI_SIDEBAND_SUSPEND)
>
> ifdef in .c files are messy and hard to maintain.
>
> Also, why is an xhci-specific option enabling/disabling core USB
> functions like this? Shouldn't it be a generic USB config option name
> instead?
>
To address the above 2 suggestions, I'll move related codes into a new
file offload.c, and create a new config to manage them.
> > +int usb_offload_get(struct usb_device *udev)
> > +{
> > + int ret;
> > +
> > + usb_lock_device(udev);
> > + if (udev->state == USB_STATE_NOTATTACHED) {
> > + ret = -ENODEV;
> > + goto unlock_device;
>
> Shouldn't we using the guard logic here instead? That would make all of
> this look much simpler and easier to maintain over time.
>
Thanks for the suggestion. Guard logics would be adapted in the next version.
> > +
> > + if (ret < 0)
>
> Why the blank line?
>
I'll remove the blank line. Thanks for the heads up.
> > +bool usb_offload_check(struct usb_device *udev)
> > +{
> > + struct usb_device *child;
> > + bool active;
> > + int port1;
> > +
> > + usb_hub_for_each_child(udev, port1, child) {
> > + usb_lock_device(child);
> > + active = usb_offload_check(child);
> > + usb_unlock_device(child);
> > + if (active)
> > + return true;
> > + }
> > +
> > + return !!udev->offload_usage;
>
> I think you forgot to mark this function as requiring that the lock be
> held, right? Just documenting it isn't going to be simple to notice or
> maintain over time...
>
> thanks,
>
> greg k-h
__must_hold marco would be added in the next version. Thanks for the heads up.
Regards,
Guan-Yu
^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH v13 3/4] xhci: sideband: add api to trace sideband usage
2025-05-28 9:04 [PATCH v13 0/4] Support system sleep with offloaded usb transfers Guan-Yu Lin
2025-05-28 9:04 ` [PATCH v13 1/4] usb: xhci-plat: separate dev_pm_ops for each pm_event Guan-Yu Lin
2025-05-28 9:04 ` [PATCH v13 2/4] usb: add apis for offload usage tracking Guan-Yu Lin
@ 2025-05-28 9:04 ` Guan-Yu Lin
2025-05-28 9:04 ` [PATCH v13 4/4] usb: host: enable USB offload during system sleep Guan-Yu Lin
3 siblings, 0 replies; 7+ messages in thread
From: Guan-Yu Lin @ 2025-05-28 9:04 UTC (permalink / raw)
To: gregkh, mathias.nyman, gargaditya08, kekrby, jeff.johnson,
quic_zijuhu, andriy.shevchenko, ben, broonie, quic_wcheng,
krzysztof.kozlowski
Cc: linux-usb, linux-kernel, Guan-Yu Lin
The existing sideband driver only registers sidebands without tracking
their active usage. To address this, sideband will now record its active
usage when it creates/removes interrupters. In addition, a new api is
introduced to provide a means for other dirvers to fetch sideband
activity information on a USB host controller.
Signed-off-by: Guan-Yu Lin <guanyulin@google.com>
---
drivers/usb/host/xhci-sideband.c | 38 +++++++++++++++++++++++++++++++
include/linux/usb/xhci-sideband.h | 9 ++++++++
2 files changed, 47 insertions(+)
diff --git a/drivers/usb/host/xhci-sideband.c b/drivers/usb/host/xhci-sideband.c
index d49f9886dd84..15d72c23c0e0 100644
--- a/drivers/usb/host/xhci-sideband.c
+++ b/drivers/usb/host/xhci-sideband.c
@@ -266,6 +266,33 @@ xhci_sideband_get_event_buffer(struct xhci_sideband *sb)
}
EXPORT_SYMBOL_GPL(xhci_sideband_get_event_buffer);
+#if IS_ENABLED(CONFIG_USB_XHCI_SIDEBAND_SUSPEND)
+/**
+ * xhci_sideband_check - check the existence of active sidebands
+ * @hcd: the host controller driver associated with the target host controller
+ *
+ * Allow other drivers, such as usb controller driver, to check if there are
+ * any sideband activity on the host controller. This information could be used
+ * for power management or other forms of resource management. The caller should
+ * ensure downstream usb devices are all either suspended or marked as
+ * "offload_at_suspend" to ensure the correctness of the return value.
+ *
+ * Returns true on any active sideband existence, false otherwise.
+ */
+bool xhci_sideband_check(struct usb_hcd *hcd)
+{
+ struct usb_device *udev = hcd->self.root_hub;
+ bool active;
+
+ usb_lock_device(udev);
+ active = usb_offload_check(udev);
+ usb_unlock_device(udev);
+
+ return active;
+}
+EXPORT_SYMBOL_GPL(xhci_sideband_check);
+#endif /* IS_ENABLED(CONFIG_USB_XHCI_SIDEBAND_SUSPEND) */
+
/**
* xhci_sideband_create_interrupter - creates a new interrupter for this sideband
* @sb: sideband instance for this usb device
@@ -286,6 +313,7 @@ xhci_sideband_create_interrupter(struct xhci_sideband *sb, int num_seg,
bool ip_autoclear, u32 imod_interval, int intr_num)
{
int ret = 0;
+ struct usb_device *udev;
if (!sb || !sb->xhci)
return -ENODEV;
@@ -304,6 +332,9 @@ xhci_sideband_create_interrupter(struct xhci_sideband *sb, int num_seg,
goto out;
}
+ udev = sb->vdev->udev;
+ ret = usb_offload_get(udev);
+
sb->ir->ip_autoclear = ip_autoclear;
out:
@@ -323,6 +354,8 @@ EXPORT_SYMBOL_GPL(xhci_sideband_create_interrupter);
void
xhci_sideband_remove_interrupter(struct xhci_sideband *sb)
{
+ struct usb_device *udev;
+
if (!sb || !sb->ir)
return;
@@ -330,6 +363,11 @@ xhci_sideband_remove_interrupter(struct xhci_sideband *sb)
xhci_remove_secondary_interrupter(xhci_to_hcd(sb->xhci), sb->ir);
sb->ir = NULL;
+ udev = sb->vdev->udev;
+
+ if (udev->state != USB_STATE_NOTATTACHED)
+ usb_offload_put(udev);
+
mutex_unlock(&sb->mutex);
}
EXPORT_SYMBOL_GPL(xhci_sideband_remove_interrupter);
diff --git a/include/linux/usb/xhci-sideband.h b/include/linux/usb/xhci-sideband.h
index 45288c392f6e..5174cc5afc98 100644
--- a/include/linux/usb/xhci-sideband.h
+++ b/include/linux/usb/xhci-sideband.h
@@ -11,6 +11,7 @@
#include <linux/scatterlist.h>
#include <linux/usb.h>
+#include <linux/usb/hcd.h>
#define EP_CTX_PER_DEV 31 /* FIXME defined twice, from xhci.h */
@@ -83,6 +84,14 @@ xhci_sideband_get_endpoint_buffer(struct xhci_sideband *sb,
struct usb_host_endpoint *host_ep);
struct sg_table *
xhci_sideband_get_event_buffer(struct xhci_sideband *sb);
+
+#if IS_ENABLED(CONFIG_USB_XHCI_SIDEBAND_SUSPEND)
+bool xhci_sideband_check(struct usb_hcd *hcd);
+#else
+static inline bool xhci_sideband_check(struct usb_hcd *hcd)
+{ return false; }
+#endif /* IS_ENABLED(CONFIG_USB_XHCI_SIDEBAND_SUSPEND) */
+
int
xhci_sideband_create_interrupter(struct xhci_sideband *sb, int num_seg,
bool ip_autoclear, u32 imod_interval, int intr_num);
--
2.49.0.1164.gab81da1b16-goog
^ permalink raw reply related [flat|nested] 7+ messages in thread* [PATCH v13 4/4] usb: host: enable USB offload during system sleep
2025-05-28 9:04 [PATCH v13 0/4] Support system sleep with offloaded usb transfers Guan-Yu Lin
` (2 preceding siblings ...)
2025-05-28 9:04 ` [PATCH v13 3/4] xhci: sideband: add api to trace sideband usage Guan-Yu Lin
@ 2025-05-28 9:04 ` Guan-Yu Lin
3 siblings, 0 replies; 7+ messages in thread
From: Guan-Yu Lin @ 2025-05-28 9:04 UTC (permalink / raw)
To: gregkh, mathias.nyman, gargaditya08, kekrby, jeff.johnson,
quic_zijuhu, andriy.shevchenko, ben, broonie, quic_wcheng,
krzysztof.kozlowski
Cc: linux-usb, linux-kernel, Guan-Yu Lin
Sharing a USB controller with another entity via xhci-sideband driver
creates power management complexities. To prevent the USB controller
from being inadvertently deactivated while in use by the other entity, a
usage-count based mechanism is implemented. This allows the system to
manage power effectively, ensuring the controller remains available
whenever needed.
In order to maintain full functionality of an offloaded USB devices,
several changes are made within the suspend flow of such devices:
- skip usb_suspend_device() so that the port/hub are still active for
USB transfers via offloaded path.
- not suspending the endpoints which are used by USB interfaces marked
with needs_remote_wakeup. Namely, skip usb_suspend_interface() and
usb_hcd_flush_endpoint() on associated USB interfaces. This reserves a
pending interrupt urb during system suspend for handling the interrupt
transfer, which is necessary since remote wakeup doesn't apply in the
offloaded USB devices when controller is still active.
- not flushing the endpoints of actively offloaded USB devices. Given
that the USB devices is used by another entity, unilaterally flush the
endpoint might lead to unexpected behavior on another entity.
- not suspending the xhci controller. This is done by skipping the
suspend/resume callbacks in the xhci platform driver.
Signed-off-by: Guan-Yu Lin <guanyulin@google.com>
---
drivers/usb/core/driver.c | 50 +++++++++++++++++++++++++++++++-----
drivers/usb/host/xhci-plat.c | 19 ++++++++++++++
drivers/usb/host/xhci-plat.h | 1 +
3 files changed, 64 insertions(+), 6 deletions(-)
diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 0690619454fe..9670c10f4ade 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -1420,11 +1420,28 @@ static int usb_suspend_both(struct usb_device *udev, pm_message_t msg)
udev->state == USB_STATE_SUSPENDED)
goto done;
+ if (msg.event == PM_EVENT_SUSPEND && usb_offload_check(udev)) {
+ dev_dbg(&udev->dev, "device offloaded, skip suspend.\n");
+ udev->offload_at_suspend = 1;
+ }
+
/* Suspend all the interfaces and then udev itself */
if (udev->actconfig) {
n = udev->actconfig->desc.bNumInterfaces;
for (i = n - 1; i >= 0; --i) {
intf = udev->actconfig->interface[i];
+ /*
+ * Don't suspend interfaces with remote wakeup while
+ * the controller is active. This preserves pending
+ * interrupt urbs, allowing interrupt events to be
+ * handled during system suspend.
+ */
+ if (udev->offload_at_suspend &&
+ intf->needs_remote_wakeup) {
+ dev_dbg(&intf->dev,
+ "device offloaded, skip suspend.\n");
+ continue;
+ }
status = usb_suspend_interface(udev, intf, msg);
/* Ignore errors during system sleep transitions */
@@ -1435,7 +1452,8 @@ static int usb_suspend_both(struct usb_device *udev, pm_message_t msg)
}
}
if (status == 0) {
- status = usb_suspend_device(udev, msg);
+ if (!udev->offload_at_suspend)
+ status = usb_suspend_device(udev, msg);
/*
* Ignore errors from non-root-hub devices during
@@ -1480,9 +1498,11 @@ static int usb_suspend_both(struct usb_device *udev, pm_message_t msg)
*/
} else {
udev->can_submit = 0;
- for (i = 0; i < 16; ++i) {
- usb_hcd_flush_endpoint(udev, udev->ep_out[i]);
- usb_hcd_flush_endpoint(udev, udev->ep_in[i]);
+ if (!udev->offload_at_suspend) {
+ for (i = 0; i < 16; ++i) {
+ usb_hcd_flush_endpoint(udev, udev->ep_out[i]);
+ usb_hcd_flush_endpoint(udev, udev->ep_in[i]);
+ }
}
}
@@ -1524,17 +1544,35 @@ static int usb_resume_both(struct usb_device *udev, pm_message_t msg)
udev->can_submit = 1;
/* Resume the device */
- if (udev->state == USB_STATE_SUSPENDED || udev->reset_resume)
- status = usb_resume_device(udev, msg);
+ if (udev->state == USB_STATE_SUSPENDED || udev->reset_resume) {
+ if (!udev->offload_at_suspend)
+ status = usb_resume_device(udev, msg);
+ else
+ dev_dbg(&udev->dev,
+ "device offloaded, skip resume.\n");
+ }
/* Resume the interfaces */
if (status == 0 && udev->actconfig) {
for (i = 0; i < udev->actconfig->desc.bNumInterfaces; i++) {
intf = udev->actconfig->interface[i];
+ /*
+ * Interfaces with remote wakeup aren't suspended
+ * while the controller is active. This preserves
+ * pending interrupt urbs, allowing interrupt events
+ * to be handled during system suspend.
+ */
+ if (udev->offload_at_suspend &&
+ intf->needs_remote_wakeup) {
+ dev_dbg(&intf->dev,
+ "device offloaded, skip resume.\n");
+ continue;
+ }
usb_resume_interface(udev, intf, msg,
udev->reset_resume);
}
}
+ udev->offload_at_suspend = 0;
usb_mark_last_busy(udev);
done:
diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
index 9843d3ad5cf4..598f1b974347 100644
--- a/drivers/usb/host/xhci-plat.c
+++ b/drivers/usb/host/xhci-plat.c
@@ -20,6 +20,7 @@
#include <linux/acpi.h>
#include <linux/usb/of.h>
#include <linux/reset.h>
+#include <linux/usb/xhci-sideband.h>
#include "xhci.h"
#include "xhci-plat.h"
@@ -483,6 +484,15 @@ static int xhci_plat_suspend_common(struct device *dev)
static int xhci_plat_suspend(struct device *dev)
{
+ struct usb_hcd *hcd = dev_get_drvdata(dev);
+ struct xhci_plat_priv *priv = hcd_to_xhci_priv(hcd);
+
+ if (xhci_sideband_check(hcd)) {
+ priv->sideband_at_suspend = 1;
+ dev_dbg(dev, "sideband instance active, skip suspend.\n");
+ return 0;
+ }
+
return xhci_plat_suspend_common(dev);
}
@@ -535,6 +545,15 @@ static int xhci_plat_resume_common(struct device *dev, bool power_lost)
static int xhci_plat_resume(struct device *dev)
{
+ struct usb_hcd *hcd = dev_get_drvdata(dev);
+ struct xhci_plat_priv *priv = hcd_to_xhci_priv(hcd);
+
+ if (priv->sideband_at_suspend) {
+ priv->sideband_at_suspend = 0;
+ dev_dbg(dev, "sideband instance active, skip resume.\n");
+ return 0;
+ }
+
return xhci_plat_resume_common(dev, false);
}
diff --git a/drivers/usb/host/xhci-plat.h b/drivers/usb/host/xhci-plat.h
index fe4f95e690fa..2b32a93d2b76 100644
--- a/drivers/usb/host/xhci-plat.h
+++ b/drivers/usb/host/xhci-plat.h
@@ -16,6 +16,7 @@ struct xhci_plat_priv {
const char *firmware_name;
unsigned long long quirks;
bool power_lost;
+ unsigned sideband_at_suspend:1;
void (*plat_start)(struct usb_hcd *);
int (*init_quirk)(struct usb_hcd *);
int (*suspend_quirk)(struct usb_hcd *);
--
2.49.0.1164.gab81da1b16-goog
^ permalink raw reply related [flat|nested] 7+ messages in thread