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>
(cherry picked from commit
4f48203881ce947a0cbd8ae7b1a1a1b04aaa3766)
Cherry picked from upstream's gregkh/usb.git/usb-next
Conflicts:
drivers/usb/core/Kconfig (trivial merge with old deprecated configs)
drivers/usb/core/quirks.c (renamed USB_QUIRK_RESET to the older
USB_QUIRK_RESET_MORPHS)
BUG=None
TEST=None
Change-Id: Ib63d2ed955e2916598d5ecd2d75aab9260594368
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/49015
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
Reviewed-by: Sameer Nanda <snanda@chromium.org>
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_DEVICEFS
bool "USB device filesystem (DEPRECATED)"
depends on USB
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_MORPHS))
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_MORPHS))
+ /* 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 */
}