xhci: workaround CSS timeout on AMD SNPS 3.0 xHC

[mirror_ubuntu-bionic-kernel.git] / drivers / usb / host / xhci.c

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 2ad8d16811f50da72379366befd34d5a776b5f24..c700bfb809df903b38685ba04c62d0b4561c1a2c 100644 (file)
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -866,6 +866,7 @@ int xhci_suspend(struct xhci_hcd *xhci, bool do_wakeup)
        unsigned int            delay = XHCI_MAX_HALT_USEC;
        struct usb_hcd          *hcd = xhci_to_hcd(xhci);
        u32                     command;
+       u32                     res;
 
        if (!hcd->state)
                return 0;
@@ -919,11 +920,28 @@ int xhci_suspend(struct xhci_hcd *xhci, bool do_wakeup)
        command = readl(&xhci->op_regs->command);
        command |= CMD_CSS;
        writel(command, &xhci->op_regs->command);
+       xhci->broken_suspend = 0;
        if (xhci_handshake(&xhci->op_regs->status,
                                STS_SAVE, 0, 10 * 1000)) {
-               xhci_warn(xhci, "WARN: xHC save state timeout\n");
-               spin_unlock_irq(&xhci->lock);
-               return -ETIMEDOUT;
+       /*
+        * AMD SNPS xHC 3.0 occasionally does not clear the
+        * SSS bit of USBSTS and when driver tries to poll
+        * to see if the xHC clears BIT(8) which never happens
+        * and driver assumes that controller is not responding
+        * and times out. To workaround this, its good to check
+        * if SRE and HCE bits are not set (as per xhci
+        * Section 5.4.2) and bypass the timeout.
+        */
+               res = readl(&xhci->op_regs->status);
+               if ((xhci->quirks & XHCI_SNPS_BROKEN_SUSPEND) &&
+                   (((res & STS_SRE) == 0) &&
+                               ((res & STS_HCE) == 0))) {
+                       xhci->broken_suspend = 1;
+               } else {
+                       xhci_warn(xhci, "WARN: xHC save state timeout\n");
+                       spin_unlock_irq(&xhci->lock);
+                       return -ETIMEDOUT;
+               }
        }
        spin_unlock_irq(&xhci->lock);
 
@@ -976,7 +994,7 @@ int xhci_resume(struct xhci_hcd *xhci, bool hibernated)
        set_bit(HCD_FLAG_HW_ACCESSIBLE, &xhci->shared_hcd->flags);
 
        spin_lock_irq(&xhci->lock);
-       if (xhci->quirks & XHCI_RESET_ON_RESUME)
+       if ((xhci->quirks & XHCI_RESET_ON_RESUME) || xhci->broken_suspend)
                hibernated = true;
 
        if (!hibernated) {