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
to my tty git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-testing branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will be merged to the tty-next branch sometime soon,
after it pasts testing, and the merge window is open.
If you have any questions about this process, please let me know.
>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
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>
Cc: <stable@xxxxxxxxxxxxxxx> # 3.12+
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/atmel_serial.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index 756f567527c4..c6621dc296c0 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -2596,6 +2596,12 @@ static int atmel_serial_probe(struct platform_device *pdev)
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 platform_device *pdev)
*/
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:
--
2.2.1
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