xhci: fix portsc writes

Check for port reset first and skip everything else then.
Add sanity checks for PLS updates.
Add PLC notification when entering PLS_U0 state.

This gets host-initiated port resume going on win8.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

hw/usb/hcd-xhci.c

@@ -2592,6 +2592,7 @@ static void xhci_port_notify(XHCIPort *port, uint32_t bits)
     if ((port->portsc & bits) == bits) {
         return;
     }
+    trace_usb_xhci_port_notify(port->portnr, bits);
     port->portsc |= bits;
     if (!xhci_running(port->xhci)) {
         return;
@@ -2798,29 +2799,56 @@ static void xhci_port_write(void *ptr, hwaddr reg,
                             uint64_t val, unsigned size)
 {
     XHCIPort *port = ptr;
-    uint32_t portsc;
+    uint32_t portsc, notify;
 
     trace_usb_xhci_port_write(port->portnr, reg, val);
 
     switch (reg) {
     case 0x00: /* PORTSC */
+        /* write-1-to-start bits */
+        if (val & PORTSC_PR) {
+            xhci_port_reset(port);
+            break;
+        }
+
         portsc = port->portsc;
+        notify = 0;
         /* write-1-to-clear bits*/
         portsc &= ~(val & (PORTSC_CSC|PORTSC_PEC|PORTSC_WRC|PORTSC_OCC|
                            PORTSC_PRC|PORTSC_PLC|PORTSC_CEC));
         if (val & PORTSC_LWS) {
             /* overwrite PLS only when LWS=1 */
-            uint32_t pls = get_field(val, PORTSC_PLS);
-            set_field(&portsc, pls, PORTSC_PLS);
-            trace_usb_xhci_port_link(port->portnr, pls);
+            uint32_t old_pls = get_field(port->portsc, PORTSC_PLS);
+            uint32_t new_pls = get_field(val, PORTSC_PLS);
+            switch (new_pls) {
+            case PLS_U0:
+                if (old_pls != PLS_U0) {
+                    set_field(&portsc, new_pls, PORTSC_PLS);
+                    trace_usb_xhci_port_link(port->portnr, new_pls);
+                    notify = PORTSC_PLC;
+                }
+                break;
+            case PLS_U3:
+                if (old_pls < PLS_U3) {
+                    set_field(&portsc, new_pls, PORTSC_PLS);
+                    trace_usb_xhci_port_link(port->portnr, new_pls);
+                }
+                break;
+            case PLS_RESUME:
+                /* windows does this for some reason, don't spam stderr */
+                break;
+            default:
+                fprintf(stderr, "%s: ignore pls write (old %d, new %d)\n",
+                        __func__, old_pls, new_pls);
+                break;
+            }
         }
         /* read/write bits */
         portsc &= ~(PORTSC_PP|PORTSC_WCE|PORTSC_WDE|PORTSC_WOE);
         portsc |= (val & (PORTSC_PP|PORTSC_WCE|PORTSC_WDE|PORTSC_WOE));
         port->portsc = portsc;
-        /* write-1-to-start bits */
-        if (val & PORTSC_PR) {
-            xhci_port_reset(port);
+        if (notify) {
+            xhci_port_notify(port, notify);
         }
         break;
     case 0x04: /* PORTPMSC */

trace-events

@@ -362,6 +362,7 @@ usb_xhci_queue_event(uint32_t vector, uint32_t idx, const char *trb, const char
 usb_xhci_fetch_trb(uint64_t addr, const char *name, uint64_t param, uint32_t status, uint32_t control) "addr %016" PRIx64 ", %s, p %016" PRIx64 ", s %08x, c 0x%08x"
 usb_xhci_port_reset(uint32_t port) "port %d"
 usb_xhci_port_link(uint32_t port, uint32_t pls) "port %d, pls %d"
+usb_xhci_port_notify(uint32_t port, uint32_t pls) "port %d, bits %x"
 usb_xhci_slot_enable(uint32_t slotid) "slotid %d"
 usb_xhci_slot_disable(uint32_t slotid) "slotid %d"
 usb_xhci_slot_address(uint32_t slotid) "slotid %d"