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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 Bießmann <andreas.devel@googlemail.com>
This commit is contained in:
Xu, Hong 2011-08-02 01:05:04 +00:00 • committed by Albert ARIBAUD
parent 88461f164e
commit 1f4faedd51
1 changed files with 10 additions and 1 deletions
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11
drivers/serial/atmel_usart.c
View file

@ -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;
}