[PATCH v2 2/5] hw/char: cadence_uart: Disable transmit when input clock is disabled

From: Bin Meng <bmeng.cn@gmail.com>
To: "Damien Hedde" <damien.hedde@greensocs.com>,
	"Edgar E . Iglesias" <edgar.iglesias@xilinx.com>,
	"Alistair Francis" <alistair.francis@wdc.com>,
	"Peter Maydell" <peter.maydell@linaro.org>,
	"Philippe Mathieu-Daudé" <f4bug@amsat.org>
Cc: qemu-arm@nongnu.org, qemu-devel@nongnu.org
Subject: [PATCH v2 2/5] hw/char: cadence_uart: Disable transmit when input clock is disabled
Date: Wed,  1 Sep 2021 11:27:21 +0800	[thread overview]
Message-ID: <20210901032724.23256-3-bmeng.cn@gmail.com> (raw)
In-Reply-To: <20210901032724.23256-1-bmeng.cn@gmail.com>

At present when input clock is disabled, any character transmitted
to tx fifo can still show on the serial line, which is wrong.

Fixes: b636db306e06 ("hw/char/cadence_uart: add clock support")
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
---

(no changes since v1)

 hw/char/cadence_uart.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/hw/char/cadence_uart.c b/hw/char/cadence_uart.c
index b4b5e8a3ee..154be34992 100644
--- a/hw/char/cadence_uart.c
+++ b/hw/char/cadence_uart.c
@@ -327,6 +327,11 @@ static gboolean cadence_uart_xmit(void *do_not_use, GIOCondition cond,
 static void uart_write_tx_fifo(CadenceUARTState *s, const uint8_t *buf,
                                int size)
 {
+    /* ignore characters when unclocked or in reset */
+    if (!clock_is_enabled(s->refclk) || device_is_in_reset(DEVICE(s))) {
+        return;
+    }
+
     if ((s->r[R_CR] & UART_CR_TX_DIS) || !(s->r[R_CR] & UART_CR_TX_EN)) {
         return;
     }
-- 
2.25.1


