Patch set updated for coreboot: libpayload: xhci: Add delay to get reset working more reliably

[Patrick Georgi]

Patrick Georgi ([e-mail]) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/12325

-gerrit

commit 9bce072cf13125222ca87ce66f41f3a309d02210
Author: Rajmohan Mani 
Date:   Fri Oct 30 17:00:24 2015 -0700

libpayload: xhci: Add delay to get reset working more reliably

Existing Intel xHCI controllers require a delay of 1 ms,
    after setting the CMD_RESET bit in command register, before
    accessing any HC registers. This allows the HC to complete
    the reset operation and be ready for HC register access.
    Without this delay, the subsequent HC register access,
    may result in a system hang, very rarely.

Verified CherryView / Braswell platforms go through over
    1000 warm reboot cycles (which was not possible without
    this patch), without any xHCI reset hang in depthcharge.

BRANCH=None
    BUG=None
    TEST=Verified CherryView / Braswell platforms go through
    over 1000 warm reboot cycles, without any xHCI reset hang
    in depthcharge.

Change-Id: I8eff5115ca52738bdcf8bc65fbfb2a5f60a0abe1
    Signed-off-by: Patrick Georgi 
    Original-Commit-Id: 3e7ea70df36e3bf35a6ee1297640900ee76bfdac
    Original-Change-Id: Id681a19d0eedb0e2c29e259c5467bcde577e3460
    Original-Signed-off-by: Rajmohan Mani 
    Original-Reviewed-on: https://chromium-review.googlesource.com/310022
    Original-Reviewed-by: Patrick Georgi 
---
 payloads/libpayload/drivers/usb/xhci.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/payloads/libpayload/drivers/usb/xhci.c b/payloads/libpayload/drivers/usb/xhci.c
index 71272c7..d223d0f 100644
--- a/payloads/libpayload/drivers/usb/xhci.c
+++ b/payloads/libpayload/drivers/usb/xhci.c
@@ -328,6 +328,17 @@ xhci_reset(hci_t *const controller)
    xhci_stop(controller);

xhci->opreg->usbcmd |= USBCMD_HCRST;
+
+	/* Existing Intel xHCI controllers require a delay of 1 ms,
+	 * after setting the CMD_RESET bit, and before accessing any
+	 * HC registers. This allows the HC to complete the
+	 * reset operation and be ready for HC register access.
+	 * Without this delay, the subsequent HC register access,
+	 * may result in a system hang very rarely.
+	 */
+	if (IS_ENABLED(CONFIG_LP_ARCH_X86))
+		mdelay(1);
+
    xhci_debug("Resetting controller... ");
    if (!xhci_handshake(&xhci->opreg->usbcmd, USBCMD_HCRST, 0, 1000000L))
    	usb_debug("timeout!\n");