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xhci: workaround for hosts missing CAS bit

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If a device is unplugged and replugged during Sx system suspend
some  Intel xHC hosts will overwrite the CAS (Cold attach status) flag
and no device connection is noticed in resume.

A device in this state can be identified in resume if its link state
is in polling or compliance mode, and the current connect status is 0.
A device in this state needs to be warm reset.

Intel 100/c230 series PCH specification update Doc #332692-006 Errata #8

Observed on Cherryview and Apollolake as they go into compliance mode
if LFPS times out during polling, and re-plugged devices are not
discovered at resume.

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
CC: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Mathias Nyman
2016-10-20 18:09:19 +03:00
committed by Greg Kroah-Hartman
parent 4c39135aa4
commit 346e99736c
3 changed files with 46 additions and 0 deletions
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37
drivers/usb/host/xhci-hub.c
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@@ -1355,6 +1355,35 @@ int xhci_bus_suspend(struct usb_hcd *hcd)
return 0;
}
/*
* Workaround for missing Cold Attach Status (CAS) if device re-plugged in S3.
* warm reset a USB3 device stuck in polling or compliance mode after resume.
* See Intel 100/c230 series PCH specification update Doc #332692-006 Errata #8
*/
static bool xhci_port_missing_cas_quirk(int port_index,
__le32 __iomem **port_array)
{
u32 portsc;
portsc = readl(port_array[port_index]);
/* if any of these are set we are not stuck */
if (portsc & (PORT_CONNECT | PORT_CAS))
return false;
if (((portsc & PORT_PLS_MASK) != XDEV_POLLING) &&
((portsc & PORT_PLS_MASK) != XDEV_COMP_MODE))
return false;
/* clear wakeup/change bits, and do a warm port reset */
portsc &= ~(PORT_RWC_BITS | PORT_CEC | PORT_WAKE_BITS);
portsc |= PORT_WR;
writel(portsc, port_array[port_index]);
/* flush write */
readl(port_array[port_index]);
return true;
}
int xhci_bus_resume(struct usb_hcd *hcd)
{
struct xhci_hcd *xhci = hcd_to_xhci(hcd);
@@ -1392,6 +1421,14 @@ int xhci_bus_resume(struct usb_hcd *hcd)
u32 temp;
temp = readl(port_array[port_index]);
/* warm reset CAS limited ports stuck in polling/compliance */
if ((xhci->quirks & XHCI_MISSING_CAS) &&
(hcd->speed >= HCD_USB3) &&
xhci_port_missing_cas_quirk(port_index, port_array)) {
xhci_dbg(xhci, "reset stuck port %d\n", port_index);
continue;
}
if (DEV_SUPERSPEED_ANY(temp))
temp &= ~(PORT_RWC_BITS | PORT_CEC | PORT_WAKE_BITS);
else