From da15ca01bf16dfb5741f8953d437d038144b8de9 Mon Sep 17 00:00:00 2001
From: Harald Welte <laforge@gnumonks.org>
Date: Thu, 17 Mar 2016 21:14:04 +0100
Subject: [PATCH] mode_cardemu: mask the USART status register with mask
 register

otherwise it might be reacting on stale bits in CSR, which actually are
no longer able to cause any interrupts.
---
 firmware/src_simtrace/mode_cardemu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/firmware/src_simtrace/mode_cardemu.c b/firmware/src_simtrace/mode_cardemu.c
index ece4da8c..e51e9905 100644
--- a/firmware/src_simtrace/mode_cardemu.c
+++ b/firmware/src_simtrace/mode_cardemu.c
@@ -145,7 +145,7 @@ void usart_irq_rx(uint8_t uart)
 	if (uart == 1)
 		ci = &cardem_inst[1];
 #endif
-	csr = usart->US_CSR;
+	csr = usart->US_CSR & usart->US_IMR;
 
 	if (csr & US_CSR_RXRDY) {
         	byte = (usart->US_RHR) & 0xFF;