Commit 9214d1d8 set the USB persist flag as a default for all devices. This might be desirable for some distributions, but it certainly has its trade-offs... most importantly, it can significantly increase system resume time, because the kernel blocks on resuming (and sometimes resetting) USB devices before it unfreezes userspace. This patch introduces a new config option CONFIG_USB_DEFAULT_PERSIST, which allows distributions to make this decision on their own without the need to carry a custom patch or revert the kernel's setting in userspace. Signed-off-by: Julius Werner <jwerner@xxxxxxxxxxxx> --- drivers/usb/core/Kconfig | 14 ++++++++++++++ drivers/usb/core/quirks.c | 16 +++++----------- 2 files changed, 19 insertions(+), 11 deletions(-) diff --git a/drivers/usb/core/Kconfig b/drivers/usb/core/Kconfig index f70c1a1..dfc1360 100644 --- a/drivers/usb/core/Kconfig +++ b/drivers/usb/core/Kconfig @@ -27,6 +27,20 @@ config USB_ANNOUNCE_NEW_DEVICES comment "Miscellaneous USB options" depends on USB +config USB_DEFAULT_PERSIST + bool "Enable USB persist by default" + depends on USB + default y + help + Say N here if you don't want USB power session persistance + enabled by default. This will make suspended USB devices that + lose power get reenumerated as if they had been unplugged, + but may reduce your system's resume time and eliminates any + chance of file system corruption by confusing two devices with + the same vendor and product ID. The persist feature can still + be enabled for individual devices through the power/persist + sysfs node. See Documentation/usb/persist.txt for more info. + config USB_DYNAMIC_MINORS bool "Dynamic USB minor allocation" depends on USB diff --git a/drivers/usb/core/quirks.c b/drivers/usb/core/quirks.c index 3113c1d..ab5638d 100644 --- a/drivers/usb/core/quirks.c +++ b/drivers/usb/core/quirks.c @@ -201,20 +201,14 @@ void usb_detect_quirks(struct usb_device *udev) dev_dbg(&udev->dev, "USB quirks for this device: %x\n", udev->quirks); - /* For the present, all devices default to USB-PERSIST enabled */ -#if 0 /* was: #ifdef CONFIG_PM */ - /* Hubs are automatically enabled for USB-PERSIST */ - if (udev->descriptor.bDeviceClass == USB_CLASS_HUB) +#ifdef CONFIG_USB_DEFAULT_PERSIST + if (!(udev->quirks & USB_QUIRK_RESET)) udev->persist_enabled = 1; - #else - /* In the absence of PM, we can safely enable USB-PERSIST - * for all devices. It will affect things like hub resets - * and EMF-related port disables. - */ - if (!(udev->quirks & USB_QUIRK_RESET)) + /* Hubs are automatically enabled for USB-PERSIST */ + if (udev->descriptor.bDeviceClass == USB_CLASS_HUB) udev->persist_enabled = 1; -#endif /* CONFIG_PM */ +#endif /* CONFIG_USB_DEFAULT_PERSIST */ } void usb_detect_interface_quirks(struct usb_device *udev) -- 1.7.12.4 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
