[PATCH] usb: chipidea: fix RT issue for udc

[Jeaho Hwang <jhhwang@rtst.co.kr>]

hw_ep_prime sometimes fails if irq occurs while it rus on RT kernel.
to prevent local_irq_save should keep the function from irqs.

I am not sure where is the best to submit this patch, between RT and USB
community so sending to both. thanks.

Signed-off-by: Jeaho Hwang <jhhwang@rtst.co.kr>
---
 drivers/usb/chipidea/udc.c | 31 +++++++++++++++++++++++++------
 1 file changed, 25 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c
index 5f35cdd2cf1d..a90498f17cc4 100644
--- a/drivers/usb/chipidea/udc.c
+++ b/drivers/usb/chipidea/udc.c
@@ -102,6 +102,9 @@ static int hw_ep_flush(struct ci_hdrc *ci, int num, int dir)
 {
 	int n = hw_ep_bit(num, dir);
 
+    /* From zynq-7000 TRM, It can take a long time
+     * so irq disable is not a good option for RT
+     */
 	do {
 		/* flush any pending transfer */
 		hw_write(ci, OP_ENDPTFLUSH, ~0, BIT(n));
@@ -190,22 +193,32 @@ static int hw_ep_get_halt(struct ci_hdrc *ci, int num, int dir)
 static int hw_ep_prime(struct ci_hdrc *ci, int num, int dir, int is_ctrl)
 {
 	int n = hw_ep_bit(num, dir);
+	unsigned long flags;
+	int ret = 0;
 
 	/* Synchronize before ep prime */
 	wmb();
 
-	if (is_ctrl && dir == RX && hw_read(ci, OP_ENDPTSETUPSTAT, BIT(num)))
-		return -EAGAIN;
+	/* irq affects this routine so irq should be disabled on RT.
+	 * on standard kernel, irq is already disabled by callers.
+	 */
+	local_irq_save(flags);
+	if (is_ctrl && dir == RX && hw_read(ci, OP_ENDPTSETUPSTAT, BIT(num))) {
+		ret = -EAGAIN;
+	goto out;
+	}
 
 	hw_write(ci, OP_ENDPTPRIME, ~0, BIT(n));
 
 	while (hw_read(ci, OP_ENDPTPRIME, BIT(n)))
 		cpu_relax();
 	if (is_ctrl && dir == RX && hw_read(ci, OP_ENDPTSETUPSTAT, BIT(num)))
-		return -EAGAIN;
+		ret = -EAGAIN;
 
+out:
+	local_irq_restore(flags);
 	/* status shoult be tested according with manual but it doesn't work */
-	return 0;
+	return ret;
 }
 
 /**
-- 
2.25.1