From 9b790915450e2e2eb9a8df7fe32f41e895de9da1 Mon Sep 17 00:00:00 2001 From: Julius Werner Date: Fri, 17 May 2013 12:08:51 -0700 Subject: [PATCH] usb: ehci: Only sleep for post-resume handover if devices use persist The current EHCI code sleeps a flat 110ms in the resume path if there was a USB 1.1 device connected to its companion controller during suspend, waiting for the device to reappear and reset so that it can be handed back to the companion. This is necessary if the device uses persist, so that the companion controller can actually see it during its own resume path. However, if the device doesn't use persist, this is entirely unnecessary. We might just as well ignore it and have the normal device detection/reset/handoff code handle it asynchronously when it eventually shows up. As USB 1.1 devices are almost exclusively HIDs these days (for which persist has no value), this can allow distros to shave another tenth of a second off their resume time. In order to enable this optimization, the patch also adds a new usb_for_each_dev() iterator that is exported by the USB core and wraps bus_for_each_dev() with the logic to differentiate between struct usb_device and struct usb_interface on the usb_bus_type bus. Signed-off-by: Julius Werner Acked-by: Alan Stern Signed-off-by: Greg Kroah-Hartman --- drivers/usb/core/usb.c | 33 +++++++++++++++++++++++++++++++++ drivers/usb/host/ehci-hub.c | 16 ++++++++++++++++ include/linux/usb.h | 1 + 3 files changed, 50 insertions(+) diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c index b10da720f2b4..7dad603dde43 100644 --- a/drivers/usb/core/usb.c +++ b/drivers/usb/core/usb.c @@ -209,6 +209,39 @@ struct usb_interface *usb_find_interface(struct usb_driver *drv, int minor) } EXPORT_SYMBOL_GPL(usb_find_interface); +struct each_dev_arg { + void *data; + int (*fn)(struct usb_device *, void *); +}; + +static int __each_dev(struct device *dev, void *data) +{ + struct each_dev_arg *arg = (struct each_dev_arg *)data; + + /* There are struct usb_interface on the same bus, filter them out */ + if (!is_usb_device(dev)) + return 0; + + return arg->fn(container_of(dev, struct usb_device, dev), arg->data); +} + +/** + * usb_for_each_dev - iterate over all USB devices in the system + * @data: data pointer that will be handed to the callback function + * @fn: callback function to be called for each USB device + * + * Iterate over all USB devices and call @fn for each, passing it @data. If it + * returns anything other than 0, we break the iteration prematurely and return + * that value. + */ +int usb_for_each_dev(void *data, int (*fn)(struct usb_device *, void *)) +{ + struct each_dev_arg arg = {data, fn}; + + return bus_for_each_dev(&usb_bus_type, NULL, &arg, __each_dev); +} +EXPORT_SYMBOL_GPL(usb_for_each_dev); + /** * usb_release_dev - free a usb device structure when all users of it are finished. * @dev: device that's been disconnected diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c index 9ab4a4d9768a..b2f64506840b 100644 --- a/drivers/usb/host/ehci-hub.c +++ b/drivers/usb/host/ehci-hub.c @@ -42,6 +42,12 @@ static int ehci_hub_control( u16 wLength ); +static int persist_enabled_on_companion(struct usb_device *udev, void *unused) +{ + return !udev->maxchild && udev->persist_enabled && + udev->bus->root_hub->speed < USB_SPEED_HIGH; +} + /* After a power loss, ports that were owned by the companion must be * reset so that the companion can still own them. */ @@ -56,6 +62,16 @@ static void ehci_handover_companion_ports(struct ehci_hcd *ehci) if (!ehci->owned_ports) return; + /* + * USB 1.1 devices are mostly HIDs, which don't need to persist across + * suspends. If we ensure that none of our companion's devices have + * persist_enabled (by looking through all USB 1.1 buses in the system), + * we can skip this and avoid slowing resume down. Devices without + * persist will just get reenumerated shortly after resume anyway. + */ + if (!usb_for_each_dev(NULL, persist_enabled_on_companion)) + return; + /* Make sure the ports are powered */ port = HCS_N_PORTS(ehci->hcs_params); while (port--) { diff --git a/include/linux/usb.h b/include/linux/usb.h index a0bee5a28d1a..b424e5318f20 100644 --- a/include/linux/usb.h +++ b/include/linux/usb.h @@ -717,6 +717,7 @@ const struct usb_device_id *usb_match_id(struct usb_interface *interface, extern int usb_match_one_id(struct usb_interface *interface, const struct usb_device_id *id); +extern int usb_for_each_dev(void *data, int (*fn)(struct usb_device *, void *)); extern struct usb_interface *usb_find_interface(struct usb_driver *drv, int minor); extern struct usb_interface *usb_ifnum_to_if(const struct usb_device *dev, -- 2.20.1