From 1f4faedd51ee72a57afb9edba2d71ba01a2ec20e Mon Sep 17 00:00:00 2001
From: "Xu, Hong" <Hong.Xu@atmel.com>
Date: Tue, 2 Aug 2011 01:05:04 +0000
Subject: [PATCH] AT91: Small fix on AT91 USART initialization code
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Before reset dbgu transmitter, we just wait TXEMPTY to drain the
transmitter register(Just in case). If not doing this, we may sometimes
see several weird characters from DBGU.
A short delay is also added to make sure the new serial settings are
settled.
Signed-off-by: Hong Xu <hong.xu@atmel.com>
[cherry-picked from u-boot-atmel/old-next]
Signed-off-by: Andreas BieÃmann <andreas.devel@googlemail.com>
---
drivers/serial/atmel_usart.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/serial/atmel_usart.c b/drivers/serial/atmel_usart.c
index e326b2bcff..943ef70fa6 100644
--- a/drivers/serial/atmel_usart.c
+++ b/drivers/serial/atmel_usart.c
@@ -49,17 +49,26 @@ int serial_init(void)
{
atmel_usart3_t *usart = (atmel_usart3_t *)CONFIG_USART_BASE;
+ /*
+ * Just in case: drain transmitter register
+ * 1000us is enough for baudrate >= 9600
+ */
+ if (!(readl(&usart->csr) & USART3_BIT(TXEMPTY)))
+ __udelay(1000);
+
writel(USART3_BIT(RSTRX) | USART3_BIT(RSTTX), &usart->cr);
serial_setbrg();
- writel(USART3_BIT(RXEN) | USART3_BIT(TXEN), &usart->cr);
writel((USART3_BF(USART_MODE, USART3_USART_MODE_NORMAL)
| USART3_BF(USCLKS, USART3_USCLKS_MCK)
| USART3_BF(CHRL, USART3_CHRL_8)
| USART3_BF(PAR, USART3_PAR_NONE)
| USART3_BF(NBSTOP, USART3_NBSTOP_1)),
&usart->mr);
+ writel(USART3_BIT(RXEN) | USART3_BIT(TXEN), &usart->cr);
+ /* 100us is enough for the new settings to be settled */
+ __udelay(100);
return 0;
}
--
2.39.5