Change in coreboot[master]: xhci: Fix Abort command event handling

[Patrick Georgi (Code Review)]

Patrick Georgi has submitted this change. ( https://review.coreboot.org/c/coreboot/+/44875 )

Change subject: xhci: Fix Abort command event handling
......................................................................

xhci: Fix Abort command event handling

This fixes issues with how we handle events generated by the xHCI
"command abort" command. first, depending on the state of the xHCI
controller, the COMMAND_ABORTED may not be generated. If the
controller was between commands, only the COMMAND_RING_STOPPED event
will be generated. Second, do not adjust the command ring "cur"
pointer as that just confuses the controller.

BUG=b:160354585,b:157123390
TEST=able to boot into recovery using USB stick on servo v2 on volteer
    as well as HooToo 8-1 hub

Change-Id: I055df680d1797f35d9730e2bfdb4119925657168
Signed-off-by: Caveh Jalali 
Reviewed-on: https://review.coreboot.org/c/coreboot/+/44875
Tested-by: build bot (Jenkins) 
Reviewed-by: Julius Werner 
---
M payloads/libpayload/drivers/usb/xhci_events.c
1 file changed, 27 insertions(+), 7 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Julius Werner: Looks good to me, approved

diff --git a/payloads/libpayload/drivers/usb/xhci_events.c b/payloads/libpayload/drivers/usb/xhci_events.c
index 32a43fc..139ea59 100644
--- a/payloads/libpayload/drivers/usb/xhci_events.c
+++ b/payloads/libpayload/drivers/usb/xhci_events.c
@@ -226,7 +226,15 @@
    return *timeout_us;
 }

-/* returns cc of command in question (pointed to by `address`) */
+/*
+ * Ref. xHCI Specification Revision 1.2, May 2019.
+ * Section 4.6.1.2.
+ *
+ * Process events from xHCI Abort command.
+ *
+ * Returns CC_COMMAND_RING_STOPPED on success and TIMEOUT on failure.
+ */
+
 int
 xhci_wait_for_command_aborted(xhci_t *const xhci, const trb_t *const address)
 {
@@ -239,12 +247,13 @@
    int cc = TIMEOUT;
    /*
     * Expects two command completion events:
-	 * The first with CC == COMMAND_ABORTED should point to address,
+	 * The first with CC == COMMAND_ABORTED should point to address
+	 * (not present if command was not running),
     * the second with CC == COMMAND_RING_STOPPED should point to new dq.
     */
    while (xhci_wait_for_event_type(xhci, TRB_EV_CMD_CMPL, &timeout_us)) {
    	if ((xhci->er.cur->ptr_low == virt_to_phys(address)) &&
-				(xhci->er.cur->ptr_high == 0)) {
+		    (xhci->er.cur->ptr_high == 0)) {
    		cc = TRB_GET(CC, xhci->er.cur);
    		xhci_advance_event_ring(xhci);
    		break;
@@ -252,20 +261,31 @@

xhci_handle_command_completion_event(xhci);
    }
-	if (!timeout_us)
-		xhci_debug("Warning: Timed out waiting for COMMAND_ABORTED.\n");
+	if (timeout_us == 0) {
+		xhci_debug("Warning: Timed out waiting for "
+			   "COMMAND_ABORTED or COMMAND_RING_STOPPED.\n");
+		goto update_and_return;
+	}
+	if (cc == CC_COMMAND_RING_STOPPED) {
+		/* There may not have been a command to abort. */
+		goto update_and_return;
+	}
+
+	timeout_us = USB_MAX_PROCESSING_TIME_US; /* 5s */
    while (xhci_wait_for_event_type(xhci, TRB_EV_CMD_CMPL, &timeout_us)) {
    	if (TRB_GET(CC, xhci->er.cur) == CC_COMMAND_RING_STOPPED) {
-			xhci->cr.cur = phys_to_virt(xhci->er.cur->ptr_low);
+			cc = CC_COMMAND_RING_STOPPED;
    		xhci_advance_event_ring(xhci);
    		break;
    	}

xhci_handle_command_completion_event(xhci);
    }
-	if (!timeout_us)
+	if (timeout_us == 0)
    	xhci_debug("Warning: Timed out "
    		   "waiting for COMMAND_RING_STOPPED.\n");
+
+update_and_return:
    xhci_update_event_dq(xhci);
    return cc;
 }