5.15-stable review patch. If anyone has any objections, please let me know.
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From: Alan Stern stern@rowland.harvard.edu
commit 59cf445754566984fd55af19ba7146c76e6627bc upstream.
Commit 85d07c556216 ("USB: core: Unite old scheme and new scheme descriptor reads") altered the way USB devices are enumerated following detection, and in the process it messed up the initialization of SuperSpeed (or faster) devices:
[ 31.650759] usb 2-1: new SuperSpeed Plus Gen 2x1 USB device number 2 using xhci_hcd [ 31.663107] usb 2-1: device descriptor read/8, error -71 [ 31.952697] usb 2-1: new SuperSpeed Plus Gen 2x1 USB device number 3 using xhci_hcd [ 31.965122] usb 2-1: device descriptor read/8, error -71 [ 32.080991] usb usb2-port1: attempt power cycle ...
The problem was caused by the commit forgetting that in SuperSpeed or faster devices, the device descriptor uses a logarithmic encoding of the bMaxPacketSize0 value. (For some reason I thought the 255 case in the switch statement was meant for these devices, but it isn't -- it was meant for Wireless USB and is no longer needed.)
We can fix the oversight by testing for buf->bMaxPacketSize0 = 9 (meaning 512, the actual maxpacket size for ep0 on all SuperSpeed devices) and straightening out the logic that checks and adjusts our initial guesses of the maxpacket value.
Reported-and-tested-by: Thinh Nguyen Thinh.Nguyen@synopsys.com Closes: https://lore.kernel.org/linux-usb/20230810002257.nadxmfmrobkaxgnz@synopsys.c... Signed-off-by: Alan Stern stern@rowland.harvard.edu Fixes: 85d07c556216 ("USB: core: Unite old scheme and new scheme descriptor reads") Link: https://lore.kernel.org/r/8809e6c5-59d5-4d2d-ac8f-6d106658ad73@rowland.harva... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/core/hub.c | 36 ++++++++++++++++++++++++------------ 1 file changed, 24 insertions(+), 12 deletions(-)
--- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -4705,7 +4705,7 @@ static int get_bMaxPacketSize0(struct us buf, size, initial_descriptor_timeout); switch (buf->bMaxPacketSize0) { - case 8: case 16: case 32: case 64: case 255: + case 8: case 16: case 32: case 64: case 9: if (buf->bDescriptorType == USB_DT_DEVICE) { rc = buf->bMaxPacketSize0; break; @@ -4999,23 +4999,35 @@ hub_port_init(struct usb_hub *hub, struc if (retval) goto fail;
- if (maxp0 == 0xff || udev->speed >= USB_SPEED_SUPER) - i = 512; - else - i = maxp0; - if (usb_endpoint_maxp(&udev->ep0.desc) != i) { - if (udev->speed == USB_SPEED_LOW || - !(i == 8 || i == 16 || i == 32 || i == 64)) { - dev_err(&udev->dev, "Invalid ep0 maxpacket: %d\n", i); - retval = -EMSGSIZE; - goto fail; - } + /* + * Check the ep0 maxpacket guess and correct it if necessary. + * maxp0 is the value stored in the device descriptor; + * i is the value it encodes (logarithmic for SuperSpeed or greater). + */ + i = maxp0; + if (udev->speed >= USB_SPEED_SUPER) { + if (maxp0 <= 16) + i = 1 << maxp0; + else + i = 0; /* Invalid */ + } + if (usb_endpoint_maxp(&udev->ep0.desc) == i) { + ; /* Initial ep0 maxpacket guess is right */ + } else if ((udev->speed == USB_SPEED_FULL || + udev->speed == USB_SPEED_HIGH) && + (i == 8 || i == 16 || i == 32 || i == 64)) { + /* Initial guess is wrong; use the descriptor's value */ if (udev->speed == USB_SPEED_FULL) dev_dbg(&udev->dev, "ep0 maxpacket = %d\n", i); else dev_warn(&udev->dev, "Using ep0 maxpacket: %d\n", i); udev->ep0.desc.wMaxPacketSize = cpu_to_le16(i); usb_ep0_reinit(udev); + } else { + /* Initial guess is wrong and descriptor's value is invalid */ + dev_err(&udev->dev, "Invalid ep0 maxpacket: %d\n", maxp0); + retval = -EMSGSIZE; + goto fail; }
descr = usb_get_device_descriptor(udev);