[PATCH 19/22] usb: xhci: use neutral helper when resuming ports

[Niklas Neronin <niklas.neronin@linux.intel.com>]

xhci_bus_resume() sanitizes PORTSC before writing it back. Previously,
this was done by manually clearing RW1CS and Wake bits and then setting
Warm Port Reset (WPR).

Replace this with xhci_port_state_to_neutral(), which already clears
all bits with write side effects (e.g. RW1CS, RW1S, and reserved-zero
fields) and produces a safe value for writeback. Afterwards, explicitly
clear the Wake bits as required.

This also ensures that additional bits, such as reserved-zero bits
(e.g. 2, 28, 29) and RW1S bits (e.g. bit 4), are consistently cleared,
avoiding unintended effects when writing back PORTSC.

Port Link State (PLS) remains preserved by the helper, allowing the
subsequent resume logic to operate on the current link state.

Signed-off-by: Niklas Neronin <niklas.neronin@linux.intel.com>
---
 drivers/usb/host/xhci-hub.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
index 17347bca0682..06192ae95526 100644
--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -1838,8 +1838,6 @@ int xhci_bus_resume(struct usb_hcd *hcd)
 	}
 	port_index = max_ports;
 	while (port_index--) {
-		portsc = xhci_portsc_readl(ports[port_index]);
-
 		/* warm reset CAS limited ports stuck in polling/compliance */
 		if ((xhci->quirks & XHCI_MISSING_CAS) &&
 		    (hcd->speed >= HCD_USB3) &&
@@ -1849,11 +1847,17 @@ int xhci_bus_resume(struct usb_hcd *hcd)
 			clear_bit(port_index, &bus_state->bus_suspended);
 			continue;
 		}
+
+		portsc = xhci_portsc_readl(ports[port_index]);
+		portsc = xhci_port_state_to_neutral(portsc);
+
+		/* Disable wake for all ports */
+		portsc &= ~PORT_WAKE_BITS;
+
 		/* resume if we suspended the link, and it is still suspended */
-		if (test_bit(port_index, &bus_state->bus_suspended))
+		if (test_bit(port_index, &bus_state->bus_suspended)) {
 			switch (FIELD_GET(PORT_PLS_MASK, portsc)) {
 			case PLS_U3:
-				portsc = xhci_port_state_to_neutral(portsc);
 				FIELD_MODIFY(PORT_PLS_MASK, &portsc, next_state);
 				portsc |= PORT_LWS;
 				break;
@@ -1866,8 +1870,8 @@ int xhci_bus_resume(struct usb_hcd *hcd)
 					  &bus_state->bus_suspended);
 				break;
 			}
-		/* disable wake for all ports, write new link state if needed */
-		portsc &= ~(PORTSC_RW1CS_BITS | PORT_WAKE_BITS);
+		}
+
 		xhci_portsc_writel(ports[port_index], portsc);
 	}
 
-- 
2.50.1