This is a note to let you know that I've just added the patch titled
tty/serial: at91: enable peripheral clock before accessing I/O registers
to the 3.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tty-serial-at91-enable-peripheral-clock-before-accessing-i-o-registers.patch
and it can be found in the queue-3.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From d4f641876a68d1961e30c202709cc2d484f69f6f Mon Sep 17 00:00:00 2001
From: Cyrille Pitchen <cyrille.pitchen@xxxxxxxxx>
Date: Tue, 9 Dec 2014 14:31:33 +0100
Subject: tty/serial: at91: enable peripheral clock before accessing I/O registers
From: Cyrille Pitchen <cyrille.pitchen@xxxxxxxxx>
commit d4f641876a68d1961e30c202709cc2d484f69f6f upstream.
atmel_serial_probe() calls atmel_init_port(). In turn, atmel_init_port() calls
clk_disable_unprepare() to disable the peripheral clock before returning.
Later atmel_serial_probe() accesses some I/O registers such as the Mode and
Control registers for RS485 support then the Name and Version registers, through a call to
atmel_get_ip_name(), but at that moment the peripheral clock was still
disabled.
Signed-off-by: Cyrille Pitchen <cyrille.pitchen@xxxxxxxxx>
Acked-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/atmel_serial.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -2596,6 +2596,12 @@ static int atmel_serial_probe(struct pla
device_init_wakeup(&pdev->dev, 1);
platform_set_drvdata(pdev, port);
+ /*
+ * The peripheral clock has been disabled by atmel_init_port():
+ * enable it before accessing I/O registers
+ */
+ clk_prepare_enable(port->clk);
+
if (rs485_enabled) {
UART_PUT_MR(&port->uart, ATMEL_US_USMODE_NORMAL);
UART_PUT_CR(&port->uart, ATMEL_US_RTSEN);
@@ -2606,6 +2612,12 @@ static int atmel_serial_probe(struct pla
*/
atmel_get_ip_name(&port->uart);
+ /*
+ * The peripheral clock can now safely be disabled till the port
+ * is used
+ */
+ clk_disable_unprepare(port->clk);
+
return 0;
err_add_port:
Patches currently in stable-queue which might be from cyrille.pitchen@xxxxxxxxx are
queue-3.19/tty-serial-at91-fix-error-handling-in-atmel_serial_probe.patch
queue-3.19/tty-serial-at91-enable-peripheral-clock-before-accessing-i-o-registers.patch
queue-3.19/tty-serial-at91-use-correct-type-for-dma_sync_-_for_cpu-and-dma_sync_-_for_device.patch
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