3.13.11-ckt18 -stable review patch. If anyone has any objections, please let me know.
------------------
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>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
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 a49f10d..41060fb 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -2421,6 +2421,12 @@ 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 (port->rs485.flags & SER_RS485_ENABLED) {
UART_PUT_MR(&port->uart, ATMEL_US_USMODE_NORMAL);
UART_PUT_CR(&port->uart, ATMEL_US_RTSEN);
@@ -2431,6 +2437,12 @@ 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:
--
1.9.1
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