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SubjectRe: [PATCH] serial: of-serial: add PM suspend/resume support
Hi,

This patch might have a potential issue that cause system hard hung
immediately when it accesses to registers with no clock. This could
happen on many chips that mainline kernel supporting with the setting
"no_console_suspend=1" during suspend time.

On 09/23/2014 04:34 PM, Jingchang Lu wrote:
> This adds PM suspend/resume support for the of-serial driver
> to provide power management support on devices attatched to it.
>
> Signed-off-by: Jingchang Lu <jingchang.lu@freescale.com>
> ---
> drivers/tty/serial/of_serial.c | 27 +++++++++++++++++++++++++++
> 1 file changed, 27 insertions(+)
>
> diff --git a/drivers/tty/serial/of_serial.c b/drivers/tty/serial/of_serial.c
> index 27981e2..8bc2563 100644
> --- a/drivers/tty/serial/of_serial.c
> +++ b/drivers/tty/serial/of_serial.c
> @@ -240,6 +240,32 @@ static int of_platform_serial_remove(struct platform_device *ofdev)
> return 0;
> }
>
> +#ifdef CONFIG_PM_SLEEP
> +static int of_serial_suspend(struct device *dev)
> +{
> + struct of_serial_info *info = dev_get_drvdata(dev);
> +
> + serial8250_suspend_port(info->line);
> + if (info->clk)
The fix would be something like this.
if (info->clk && console_suspend_enabled)

> + clk_disable_unprepare(info->clk);
> +
> + return 0;
> +}
> +
> +static int of_serial_resume(struct device *dev)
> +{
> + struct of_serial_info *info = dev_get_drvdata(dev);
> +
> + if (info->clk)
Ditto.

Thanks,
-Joseph
> + clk_prepare_enable(info->clk);
> +
> + serial8250_resume_port(info->line);
> +
> + return 0;
> +}
> +#endif
> +static SIMPLE_DEV_PM_OPS(of_serial_pm_ops, of_serial_suspend, of_serial_resume);
> +
> /*
> * A few common types, add more as needed.
> */
> @@ -271,6 +297,7 @@ static struct platform_driver of_platform_serial_driver = {
> .name = "of_serial",
> .owner = THIS_MODULE,
> .of_match_table = of_platform_serial_table,
> + .pm = &of_serial_pm_ops,
> },
> .probe = of_platform_serial_probe,
> .remove = of_platform_serial_remove,
>


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