Change in coreboot[master]: usb/xhci: Fix timeout logic

[Patrick Georgi (Code Review)]

Patrick Georgi has submitted this change. ( https://review.coreboot.org/c/coreboot/+/41854 )

Change subject: usb/xhci: Fix timeout logic
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usb/xhci: Fix timeout logic

This fixes a logic bug in how timeouts are reported back. In the
timeout case, the original code would return -1 instead of 0. All call
sites expect a return value of 0 as the timeout indicator.

Signed-off-by: Caveh Jalali 
Change-Id: I81a888aa0a1544e55e6a680be8f3b7f6e0d87812
Reviewed-on: https://review.coreboot.org/c/coreboot/+/41854
Tested-by: build bot (Jenkins) 
Reviewed-by: Tim Wawrzynczak 
---
M payloads/libpayload/drivers/usb/xhci.c
1 file changed, 6 insertions(+), 1 deletion(-)

Approvals:
  build bot (Jenkins): Verified
  Tim Wawrzynczak: Looks good to me, approved

diff --git a/payloads/libpayload/drivers/usb/xhci.c b/payloads/libpayload/drivers/usb/xhci.c
index 07d5b16..749ff0a 100644
--- a/payloads/libpayload/drivers/usb/xhci.c
+++ b/payloads/libpayload/drivers/usb/xhci.c
@@ -129,7 +129,12 @@
 static long
 xhci_handshake(volatile u32 *const reg, u32 mask, u32 wait_for, long timeout_us)
 {
-	while ((*reg & mask) != wait_for && timeout_us--) udelay(1);
+	if (timeout_us <= 0)
+		return 0;
+	while ((*reg & mask) != wait_for && timeout_us != 0) {
+		--timeout_us;
+		udelay(1);
+	}
    return timeout_us;
 }