The patch titled
atmel_serial: fix uart/console concurrent access
has been added to the -mm tree. Its filename is
atmel_serial-fix-uart-console-concurrent-access.patch
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Subject: atmel_serial: fix uart/console concurrent access
From: Marc Pignat <marc.pignat@xxxxxxx>
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@xxxxxxx>
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/serial/atmel_serial.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff -puN drivers/serial/atmel_serial.c~atmel_serial-fix-uart-console-concurrent-access drivers/serial/atmel_serial.c
--- a/drivers/serial/atmel_serial.c~atmel_serial-fix-uart-console-concurrent-access
+++ a/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 c
{
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 c
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 c
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);
}
_
Patches currently in -mm which might be from marc.pignat@xxxxxxx are
atmel_serial-fix-uart-console-concurrent-access.patch
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