From 39d4c922b596633da86878b1a5cc881785b8e5fa Mon Sep 17 00:00:00 2001 From: Marc Pignat Date: Wed, 2 Apr 2008 13:04:42 -0700 Subject: [PATCH] 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 Signed-off-by: Haavard Skinnemoen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/serial/atmel_serial.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/serial/atmel_serial.c b/drivers/serial/atmel_serial.c index e99a28387505..430997e33fc4 100644 --- a/drivers/serial/atmel_serial.c +++ b/drivers/serial/atmel_serial.c @@ -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); } -- 2.20.1