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atmel_serial: fix uart/console concurrent access 

Strange chars appear on the serial port when a printk and a printf
happens at the same time.  This is caused by the pdc sending chars while
atmel_console_write (called from printk) is executing

Concurent access of uart and console to the same port leads to corrupted
data to be transmitted, so disable tx dma (PDC) while writing to the
console.

Signed-off-by: Marc Pignat <marc.pignat@hevs.ch>
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Marc Pignat 2008-04-02 13:04:42 -07:00 committed by Linus Torvalds
parent ba0657ff05
commit 39d4c922b5
1 changed files with 11 additions and 0 deletions
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11
drivers/serial/atmel_serial.c
View File

@ -107,6 +107,7 @@
#define UART_PUT_TPR(port,v) __raw_writel(v, (port)->membase + ATMEL_PDC_TPR)
#define UART_PUT_TCR(port,v) __raw_writel(v, (port)->membase + ATMEL_PDC_TCR)
#define UART_GET_TCR(port) __raw_readl((port)->membase + ATMEL_PDC_TCR)
static int (*atmel_open_hook)(struct uart_port *);
static void (*atmel_close_hook)(struct uart_port *);
@ -1275,6 +1276,7 @@ static void atmel_console_write(struct console *co, const char *s, u_int count)
{
struct uart_port *port = &atmel_ports[co->index].uart;
unsigned int status, imr;
unsigned int pdc_tx;
/*
* First, save IMR and then disable interrupts
@ -1282,6 +1284,10 @@ static void atmel_console_write(struct console *co, const char *s, u_int count)
imr = UART_GET_IMR(port);
UART_PUT_IDR(port, ATMEL_US_RXRDY | ATMEL_US_TXRDY);
/* Store PDC transmit status and disable it */
pdc_tx = UART_GET_PTSR(port) & ATMEL_PDC_TXTEN;
UART_PUT_PTCR(port, ATMEL_PDC_TXTDIS);
uart_console_write(port, s, count, atmel_console_putchar);
/*
@ -1291,6 +1297,11 @@ static void atmel_console_write(struct console *co, const char *s, u_int count)
do {
status = UART_GET_CSR(port);
} while (!(status & ATMEL_US_TXRDY));
/* Restore PDC transmit status */
if (pdc_tx)
UART_PUT_PTCR(port, ATMEL_PDC_TXTEN);
/* set interrupts back the way they were */
UART_PUT_IER(port, imr);
}