[PATCH 3/4] usb: musb: Fix handling interrupts for EP0 and SET ADDRESS commmand

["Pali Rohár" <pali@kernel.org>]

Interrupt for EP0 is indicated in intrtx register via first bit. It is set
for both RX and TX. First bit in intrrx register is reserved and not set.

So remove calling musb_peri_ep0() function at every iteration of udc_irq()
and musb_peri_rx() and call it only from musb_peri_tx() when correct
interrupt bit in initrtx it set.

Address from SET ADDRESS command must be set to faddr register only after
acknowledging SERV_RXPKTRDY followed by received EP0 interrupt. So prior
calling musb_peri_ep0_set_address() check for EP0 interrupt instead of
(incorrect) MUSB_INTR_SOF interrupt.

This patch fixes issue that host (computer) cannot register U-Boot USB
device and failing with errors:

    usb 1-1: new full-speed USB device number 86 using xhci_hcd
    usb 1-1: Device not responding to setup address.
    usb 1-1: Device not responding to setup address.
    usb 1-1: device not accepting address 86, error -71

U-Boot was writing address to faddr register too early and did not wait for
correct interrupt after which should update address.

Signed-off-by: Pali Roh?r <pali@kernel.org>
---
 drivers/usb/musb/musb_udc.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/usb/musb/musb_udc.c b/drivers/usb/musb/musb_udc.c
index 7c74422623..50d8bc319c 100644
--- a/drivers/usb/musb/musb_udc.c
+++ b/drivers/usb/musb/musb_udc.c
@@ -707,9 +707,7 @@ static void musb_peri_rx(u16 intr)
 {
 	unsigned int ep;
 
-	/* Check for EP0 */
-	if (0x01 & intr)
-		musb_peri_ep0();
+	/* First bit is reserved and does not indicate interrupt for EP0 */
 
 	for (ep = 1; ep < 16; ep++) {
 		if ((1 << ep) & intr)
@@ -721,9 +719,9 @@ static void musb_peri_tx(u16 intr)
 {
 	unsigned int ep;
 
-	/* Check for EP0 */
+	/* Check for EP0: first bit indicates interrupt for both RX and TX */
 	if (0x01 & intr)
-		musb_peri_ep0_tx();
+		musb_peri_ep0();
 
 	for (ep = 1; ep < 16; ep++) {
 		if ((1 << ep) & intr)
@@ -750,8 +748,6 @@ void udc_irq(void)
 			musb_peri_resume();
 		}
 
-		musb_peri_ep0();
-
 		if (MUSB_INTR_RESET & intrusb) {
 			usbd_device_event_irq(udc_device, DEVICE_RESET, 0);
 			musb_peri_reset();
@@ -790,7 +786,7 @@ void udc_irq(void)
 			if (intrtx)
 				musb_peri_tx(intrtx);
 		} else {
-			if (MUSB_INTR_SOF & intrusb) {
+			if (readw(&musbr->intrtx) & 0x1) {
 				u8 faddr;
 				faddr = readb(&musbr->faddr);
 				/*
-- 
2.20.1