diff options
| author | Julius Werner <jwerner@chromium.org> | 2013-03-13 15:57:31 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-03-29 09:29:12 -0700 |
| commit | 4f48203881ce947a0cbd8ae7b1a1a1b04aaa3766 (patch) | |
| tree | 522224ae58cbe21d4468cffb2f54af31dd7b5094 /drivers/usb/core | |
| parent | 70b55c2ad0e5c8bbbb36cedf6a37f9d029cfd403 (diff) | |
| download | linux-4f48203881ce947a0cbd8ae7b1a1a1b04aaa3766.tar.gz | |
usb: Make USB persist default configurable
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. [edited the Kconfig help text a bit - gregkh] Signed-off-by: Julius Werner <jwerner@chromium.org> Cc: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/core')
| -rw-r--r-- | drivers/usb/core/Kconfig | 16 | ||||
| -rw-r--r-- | drivers/usb/core/quirks.c | 16 |
2 files changed, 21 insertions, 11 deletions
diff --git a/drivers/usb/core/Kconfig b/drivers/usb/core/Kconfig index 175701a2dae4..7b7305e3abc8 100644 --- a/drivers/usb/core/Kconfig +++ b/drivers/usb/core/Kconfig @@ -27,6 +27,22 @@ 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. If you say N it will make suspended USB + devices that lose power get reenumerated as if they had been + unplugged, causing any mounted filesystems to be lost. The + persist feature can still be enabled for individual devices + through the power/persist sysfs node. See + Documentation/usb/persist.txt for more info. + + If you have any questions about this, say Y here, only say N + if you know exactly what you are doing. + 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 3113c1d71442..ab5638d9c707 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) |