usb: Add support for root hub port status CAS

The host controller port status register supports CAS (Cold Attach
Status) bit. This bit could be set when USB3.0 device is connected
when system is in Sx state. When the system wakes to S0 this port
status with CAS bit is reported and this port can't be used by any
device.

When CAS bit is set the port should be reset by warm reset. This
was not supported by xhci driver.

The issue was found when pendrive was connected to suspended
platform. The link state of "Compliance Mode" was reported together
with CAS bit. This link state was also not supported by xhci and
core/hub.c.

The CAS bit is defined only for xhci root hub port and it is
not supported on regular hubs. The link status is used to force
warm reset on port. Make the USB core issue a warm reset when port
is in ether the 'inactive' or 'compliance mode'. Change the xHCI driver
to report 'compliance mode' when the CAS is set. This force warm reset
on the root hub port.

This patch should be backported to stable kernels as old as 3.2, that
contain the commit 10d674a82e553cb8a1f41027bb3c3e309b3f6804 "USB: When
hot reset for USB3 fails, try warm reset."

Signed-off-by: Stanislaw Ledwon <staszek.ledwon@linux.intel.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Acked-by: Andiry Xu <andiry.xu@amd.com>
Cc: stable@vger.kernel.org

1 files changed, 10 insertions, 8 deletions

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 25a7422ee657..8fb484984c86 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -2324,12 +2324,16 @@ static unsigned hub_is_wusb(struct usb_hub *hub)
 static int hub_port_reset(struct usb_hub *hub, int port1,
                         struct usb_device *udev, unsigned int delay, bool warm);
 
-/* Is a USB 3.0 port in the Inactive state? */
-static bool hub_port_inactive(struct usb_hub *hub, u16 portstatus)
+/* Is a USB 3.0 port in the Inactive or Complinance Mode state?
+ * Port worm reset is required to recover
+ */
+static bool hub_port_warm_reset_required(struct usb_hub *hub, u16 portstatus)
 {
         return hub_is_superspeed(hub->hdev) &&
-                (portstatus & USB_PORT_STAT_LINK_STATE) ==
-                USB_SS_PORT_LS_SS_INACTIVE;
+                (((portstatus & USB_PORT_STAT_LINK_STATE) ==
+                  USB_SS_PORT_LS_SS_INACTIVE) ||
+                 ((portstatus & USB_PORT_STAT_LINK_STATE) ==
+                  USB_SS_PORT_LS_COMP_MOD)) ;
 }
 
 static int hub_port_wait_reset(struct usb_hub *hub, int port1,
@@ -2365,7 +2369,7 @@ static int hub_port_wait_reset(struct usb_hub *hub, int port1,
                          *
                          * See https://bugzilla.kernel.org/show_bug.cgi?id=41752
                          */
-                        if (hub_port_inactive(hub, portstatus)) {
+                        if (hub_port_warm_reset_required(hub, portstatus)) {
                                 int ret;
 
                                 if ((portchange & USB_PORT_STAT_C_CONNECTION))
@@ -4408,9 +4412,7 @@ static void hub_events(void)
                         /* Warm reset a USB3 protocol port if it's in
                          * SS.Inactive state.
                          */
-                        if (hub_is_superspeed(hub->hdev) &&
-                                (portstatus & USB_PORT_STAT_LINK_STATE)
-                                        == USB_SS_PORT_LS_SS_INACTIVE) {
+                        if (hub_port_warm_reset_required(hub, portstatus)) {
                                 dev_dbg(hub_dev, "warm reset port %d\n", i);
                                 hub_port_reset(hub, i, NULL,
                                                 HUB_BH_RESET_TIME, true);