This is a note to let you know that I've just added the patch titled

USB: hub: Revert commit bd0e6c9614b9 ("usb: hub: try old enumeration

to my usb git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git in the usb-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From 3155f4f40811c5d7e3c686215051acf504e05565 Mon Sep 17 00:00:00 2001

From: Alan Stern stern@rowland.harvard.edu Date: Wed, 22 Apr 2020 16:13:08 -0400 Subject: USB: hub: Revert commit bd0e6c9614b9 ("usb: hub: try old enumeration scheme first for high speed devices")

Commit bd0e6c9614b9 ("usb: hub: try old enumeration scheme first for high speed devices") changed the way the hub driver enumerates high-speed devices. Instead of using the "new" enumeration scheme first and switching to the "old" scheme if that doesn't work, we start with the "old" scheme. In theory this is better because the "old" scheme is slightly faster -- it involves resetting the device only once instead of twice.

However, for a long time Windows used only the "new" scheme. Zeng Tao said that Windows 8 and later use the "old" scheme for high-speed devices, but apparently there are some devices that don't like it. William Bader reports that the Ricoh webcam built into his Sony Vaio laptop not only doesn't enumerate under the "old" scheme, it gets hung up so badly that it won't then enumerate under the "new" scheme! Only a cold reset will fix it.

Therefore we will revert the commit and go back to trying the "new" scheme first for high-speed devices.

Reported-and-tested-by: William Bader williambader@hotmail.com Ref: https://bugzilla.kernel.org/show_bug.cgi?id=207219 Signed-off-by: Alan Stern stern@rowland.harvard.edu Fixes: bd0e6c9614b9 ("usb: hub: try old enumeration scheme first for high speed devices") CC: Zeng Tao prime.zeng@hisilicon.com CC: stable@vger.kernel.org

Link: https://lore.kernel.org/r/Pine.LNX.4.44L0.2004221611230.11262-100000@iolanth... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- Documentation/admin-guide/kernel-parameters.txt | 3 +-- drivers/usb/core/hub.c | 4 +--- 2 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index f2a93c8679e8..7bc83f3d9bdf 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -5187,8 +5187,7 @@

usbcore.old_scheme_first= [USB] Start with the old device initialization - scheme, applies only to low and full-speed devices - (default 0 = off). + scheme (default 0 = off).

usbcore.usbfs_memory_mb= [USB] Memory limit (in MB) for buffers allocated by diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index 83549f009ced..2b6565c06c23 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -2728,13 +2728,11 @@ static bool use_new_scheme(struct usb_device *udev, int retry, { int old_scheme_first_port = port_dev->quirks & USB_PORT_QUIRK_OLD_SCHEME; - int quick_enumeration = (udev->speed == USB_SPEED_HIGH);

if (udev->speed >= USB_SPEED_SUPER) return false;

- return USE_NEW_SCHEME(retry, old_scheme_first_port || old_scheme_first - || quick_enumeration); + return USE_NEW_SCHEME(retry, old_scheme_first_port || old_scheme_first); }

/* Is a USB 3.0 port in the Inactive or Compliance Mode state?