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serial: imx: enable the clocks only when the uart is used

PATCH Superseded Huang Shijie 2 participants 3 messages Jun 3, 2013 – Jun 4, 2013

Subsystems (2)
Arm i.MX and Layerscape TTY layer and serial drivers

v1 of 2 Superseded Latest is v2 →

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Huang Shijie

author
#0 lore raw

PATCH 1/1 serial: imx: enable the clocks only when the uart is used

Current code opens the clocks when the uart driver is probed. This will wastes some power if several uarts are enabled, but not really used.

So close these clocks for uart, and enable the clocks only when the uart is used.

Signed-off-by Huang Shijie <[email protected]>
---
 drivers/tty/serial/imx.c |   12 +++++++++---
 1 files changed, 9 insertions(+), 3 deletions(-)
drivers/tty/serial/imx.c +9 -3
index 72bc1db..5705fc8 100644
@@ -699,6 +699,9 @@ static int imx_startup(struct uart_port *port)
 	int retval;
 	unsigned long flags, temp;
 
+	clk_prepare_enable(sport->clk_per);
+	clk_prepare_enable(sport->clk_ipg);
+
 	imx_setup_ufcr(sport, 0);
 
 	/* disable the DREN bit (Data Ready interrupt enable) before

@@ -884,6 +887,9 @@ static void imx_shutdown(struct uart_port *port)
 
 	writel(temp, sport->port.membase + UCR1);
 	spin_unlock_irqrestore(&sport->port.lock, flags);
+
+	clk_disable_unprepare(sport->clk_per);
+	clk_disable_unprepare(sport->clk_ipg);
 }
 
 static void

@@ -1557,6 +1563,9 @@ static int serial_imx_probe(struct platform_device *pdev)
 		goto deinit;
 	platform_set_drvdata(pdev, sport);
 
+	clk_disable_unprepare(sport->clk_per);
+	clk_disable_unprepare(sport->clk_ipg);
+
 	return 0;
 deinit:
 	if (pdata && pdata->exit)

@@ -1578,9 +1587,6 @@ static int serial_imx_remove(struct platform_device *pdev)
 
 	uart_remove_one_port(&imx_reg, &sport->port);
 
-	clk_disable_unprepare(sport->clk_per);
-	clk_disable_unprepare(sport->clk_ipg);
-
 	if (pdata && pdata->exit)
 		pdata->exit(pdev);
Signature · 1 line
1.7.1
#1 lore raw

PATCH 1/1 serial: imx: enable the clocks only when the uart is used

Quoted 17 lines · Huang Shijie

Current code opens the clocks when the uart driver is probed. This will wastes some power if several uarts are enabled, but not really used.

So close these clocks for uart, and enable the clocks only when the uart is used.

Signed-off-by Huang Shijie <[email protected]>
---
 drivers/tty/serial/imx.c |   12 +++++++++---
 1 files changed, 9 insertions(+), 3 deletions(-)
drivers/tty/serial/imx.c +0 -0
index 72bc1db..5705fc8 100644

drivers/tty/serial/imx.c static int imx_startup(struct uart_port *port) · line 703

Quoted 5 lines
drivers/tty/serial/imx.c +2 -0
@@ -699,6 +699,9 @@ static int imx_startup(struct uart_port *port)
 	int retval;
 	unsigned long flags, temp;
 
+	clk_prepare_enable(sport->clk_per);
+	clk_prepare_enable(sport->clk_ipg);

You should check the return value. I've a good mind to mark these functions with __must_check...

author
#2 lore raw

PATCH 1/1 serial: imx: enable the clocks only when the uart is used

Quoted 2 lines · Russell King - ARM Linux

You should check the return value. I've a good mind to mark these functions with __must_check...

yes, that's a good idea to add the __must_check.

thanks
Huang Shijie

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