CHROMIUM: Disable USB persist system-wide by default.

This patch effectively reverts upstream commit 9214d1d8, which enabled
USB persist by default. We have long had disabled persist on ChromeOS
through an explicit sysfs write from powerd_suspend to save kernel
resume time. This change will make that solution obsolete by disabling
persist by default from the kernel, resulting in a much cleaner system
state that does not flip-flop between persist/non-persist during
suspend/resume. This will also solve issues with autosuspend on drivers
that do not provide a reset_resume method.

BUG=chrome-os-partner:17609
TEST=Boot kernel, make sure that /sys/bus/usb/devices/*/power/persist
are all zeroes (and stay that way over suspend and when plugging in more
devices).

Change-Id: If3ef6423a82aa9af0cb1b10c49da0ffa8201224a
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/45326
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
Reviewed-by: Sameer Nanda <snanda@chromium.org>

diff --git a/drivers/usb/core/quirks.c b/drivers/usb/core/quirks.c
index 4c65eb6..6672a2d 100644 (file)
--- a/drivers/usb/core/quirks.c
+++ b/drivers/usb/core/quirks.c
@@ -179,8 +179,8 @@ 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 */
+       /* ChromeOS does not use persist to decrease kernel resume time */
+#if 1          /* was: 0 */ /* was: #ifdef CONFIG_PM */
        /* Hubs are automatically enabled for USB-PERSIST */
        if (udev->descriptor.bDeviceClass == USB_CLASS_HUB)
                udev->persist_enabled = 1;