Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752715AbYC2KuA (ORCPT ); Sat, 29 Mar 2008 06:50:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750714AbYC2Ktv (ORCPT ); Sat, 29 Mar 2008 06:49:51 -0400 Received: from smtpeu1.atmel.com ([195.65.72.27]:34561 "EHLO bagnes.atmel.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750703AbYC2Ktu (ORCPT ); Sat, 29 Mar 2008 06:49:50 -0400 From: Haavard Skinnemoen To: akpm@linux-foundation.org Cc: Andrew Victor , Remy Bohmer , linux-kernel@vger.kernel.org, Marc Pignat , Haavard Skinnemoen Subject: [PATCH] atmel_serial: fix uart/console concurrent access Date: Sat, 29 Mar 2008 11:48:52 +0100 Message-Id: <1206787732-16945-1-git-send-email-haavard.skinnemoen@atmel.com> X-Mailer: git-send-email 1.5.4.3 In-Reply-To: <> References: <> X-OriginalArrivalTime: 29 Mar 2008 10:48:52.0053 (UTC) FILETIME=[7A209850:01C8918A] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2480 Lines: 69 From: Marc Pignat 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 --- Andrew, I think we want this one before 2.6.25 as well. drivers/serial/atmel_serial.c | 11 +++++++++++ 1 files changed, 11 insertions(+), 0 deletions(-) diff --git a/drivers/serial/atmel_serial.c b/drivers/serial/atmel_serial.c index e99a283..430997e 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); } -- 1.5.4.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/