[PATCH 4.14 47/67] xhci: workaround CSS timeout on AMD SNPS 3.0 xHC

Greg Kroah-Hartman
2018-12-11T15:52:55Z

From: Sandeep Singh <sandeep.singh@amd.com>

commit a7d57abcc8a5bdeb53bbf8e87558e8e0a2c2a29d upstream.

Occasionally AMD SNPS 3.0 xHC does not respond to
CSS when set, also it does not flag anything on SRE and HCE
to point the internal xHC errors on USBSTS register. This stalls
the entire system wide suspend and there is no point in stalling
just because of xHC CSS is not responding.

To work around this problem, if the xHC does not flag
anything on SRE and HCE, we can skip the CSS
timeout and allow the system to continue the suspend. Once the
system resume happens we can internally reset the controller
using XHCI_RESET_ON_RESUME quirk

Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
Signed-off-by: Sandeep Singh <Sandeep.Singh@amd.com>
cc: Nehal Shah <Nehal-bakulchandra.Shah@amd.com>
Cc: <stable@vger.kernel.org>
Tested-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/usb/host/xhci-pci.c | 4 ++++
drivers/usb/host/xhci.c | 26 ++++++++++++++++++++++----
drivers/usb/host/xhci.h | 3 +++
3 files changed, 29 insertions(+), 4 deletions(-)

--- a/drivers/usb/host/xhci-pci.c
+++ b/drivers/usb/host/xhci-pci.c
@@ -144,6 +144,10 @@ static void xhci_pci_quirks(struct devic
pdev->device == 0x43bb))
xhci->quirks |= XHCI_SUSPEND_DELAY;

+ if (pdev->vendor == PCI_VENDOR_ID_AMD &&
+ (pdev->device == 0x15e0 || pdev->device == 0x15e1))
+ xhci->quirks |= XHCI_SNPS_BROKEN_SUSPEND;
+
if (pdev->vendor == PCI_VENDOR_ID_AMD)
xhci->quirks |= XHCI_TRUST_TX_LENGTH;

--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -918,6 +918,7 @@ int xhci_suspend(struct xhci_hcd *xhci,
unsigned int delay = XHCI_MAX_HALT_USEC;
struct usb_hcd *hcd = xhci_to_hcd(xhci);
u32 command;
+ u32 res;

if (!hcd->state)
return 0;
@@ -969,11 +970,28 @@ int xhci_suspend(struct xhci_hcd *xhci,
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);

@@ -1026,7 +1044,7 @@ int xhci_resume(struct xhci_hcd *xhci, b
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) {
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1839,6 +1839,7 @@ struct xhci_hcd {
#define XHCI_SUSPEND_DELAY BIT_ULL(30)
#define XHCI_INTEL_USB_ROLE_SW BIT_ULL(31)
#define XHCI_RESET_PLL_ON_DISCONNECT BIT_ULL(34)
+#define XHCI_SNPS_BROKEN_SUSPEND BIT_ULL(35)

unsigned int num_active_eps;
unsigned int limit_active_eps;
@@ -1870,6 +1871,8 @@ struct xhci_hcd {

/* platform-specific data -- must come last */
unsigned long priv[0] __aligned(sizeof(s64));
+ /* Broken Suspend flag for SNPS Suspend resume issue */
+ u8 broken_suspend;
};

/* Platform specific overrides to generic XHCI hc_driver ops */