[PATCH 5.4 172/214] xhci: Do warm-reset when both CAS and XDEV_RESUME are set

Greg Kroah-Hartman
2020-09-01T15:33:55Z

From: Kai-Heng Feng <kai.heng.feng@canonical.com>

commit 904df64a5f4d5ebd670801d869ca0a6d6a6e8df6 upstream.

Sometimes re-plugging a USB device during system sleep renders the device
useless:
[ 173.418345] xhci_hcd 0000:00:14.0: Get port status 2-4 read: 0x14203e2, return 0x10262
...
[ 176.496485] usb 2-4: Waited 2000ms for CONNECT
[ 176.496781] usb usb2-port4: status 0000.0262 after resume, -19
[ 176.497103] usb 2-4: can't resume, status -19
[ 176.497438] usb usb2-port4: logical disconnect

Because PLS equals to XDEV_RESUME, xHCI driver reports U3 to usbcore,
despite of CAS bit is flagged.

So proritize CAS over XDEV_RESUME to let usbcore handle warm-reset for
the port.

Cc: stable <stable@vger.kernel.org>
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20200821091549.20556-3-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/usb/host/xhci-hub.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)

--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -738,15 +738,6 @@ static void xhci_hub_report_usb3_link_st
{
u32 pls = status_reg & PORT_PLS_MASK;

- /* resume state is a xHCI internal state.
- * Do not report it to usb core, instead, pretend to be U3,
- * thus usb core knows it's not ready for transfer
- */
- if (pls == XDEV_RESUME) {
- *status |= USB_SS_PORT_LS_U3;
- return;
- }
-
/* When the CAS bit is set then warm reset
* should be performed on port
*/
@@ -769,6 +760,16 @@ static void xhci_hub_report_usb3_link_st
pls |= USB_PORT_STAT_CONNECTION;
} else {
/*
+ * Resume state is an xHCI internal state. Do not report it to
+ * usb core, instead, pretend to be U3, thus usb core knows
+ * it's not ready for transfer.
+ */
+ if (pls == XDEV_RESUME) {
+ *status |= USB_SS_PORT_LS_U3;
+ return;
+ }
+
+ /*
* If CAS bit isn't set but the Port is already at
* Compliance Mode, fake a connection so the USB core
* notices the Compliance state and resets the port.