[PATCH V2] serial: imx: enable the clocks only when the uart is used

[Shawn Guo]

On Tue, Jun 04, 2013 at 09:59:33AM +0800, Huang Shijie wrote:
> 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 <b32955 at freescale.com>

Running linux-next 20130607, I just found that the serial console stops
working due to this patch.  I think the clocks need to be enabled for
console as well.

Shawn

> ---
> v1 --> v2:
> 	check the return value of clk_prepare_enable().
> ---
>  drivers/tty/serial/imx.c |   17 ++++++++++++++---
>  1 files changed, 14 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
> index 72bc1db..7cc4810 100644
> --- a/drivers/tty/serial/imx.c
> +++ b/drivers/tty/serial/imx.c
> @@ -699,6 +699,14 @@ static int imx_startup(struct uart_port *port)
>  	int retval;
>  	unsigned long flags, temp;
>  
> +	retval = clk_prepare_enable(sport->clk_per);
> +	if (retval)
> +		goto error_out1;
> +
> +	retval = clk_prepare_enable(sport->clk_ipg);
> +	if (retval)
> +		goto error_out1;
> +
>  	imx_setup_ufcr(sport, 0);
>  
>  	/* disable the DREN bit (Data Ready interrupt enable) before
> @@ -884,6 +892,9 @@ 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 +1568,9 @@ 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 +1592,6 @@ 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);
>  
> -- 
> 1.7.1
> 
> 
> 
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