Re: [PATCHv4 2/5] driver: serial: omap: prevent runtime PM for "no_console_suspend"

From: Kevin Hilman
Date: Fri Apr 26 2013 - 14:29:10 EST


Sourav Poddar <sourav.poddar@xxxxxx> writes:

> The driver manages "no_console_suspend" by preventing runtime PM
> during the suspend path, which forces the console UART to stay awake.
>
> Signed-off-by: Sourav Poddar <sourav.poddar@xxxxxx>
> Reviewed-by: Felipe Balbi <balbi@xxxxxx>
> ---
> drivers/tty/serial/omap-serial.c | 28 +++++++++++++++++++++++++++-
> 1 files changed, 27 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
> index 30d4f7a..eddff3c 100644
> --- a/drivers/tty/serial/omap-serial.c
> +++ b/drivers/tty/serial/omap-serial.c
> @@ -161,6 +161,7 @@ struct uart_omap_port {
> u32 calc_latency;
> struct work_struct qos_work;
> struct pinctrl *pins;
> + bool is_suspending;
> };
>
> #define to_uart_omap_port(p) ((container_of((p), struct uart_omap_port, port)))
> @@ -1312,6 +1313,22 @@ static struct uart_driver serial_omap_reg = {
> };
>
> #ifdef CONFIG_PM_SLEEP
> +static int serial_omap_prepare(struct device *dev)
> +{
> + struct uart_omap_port *up = dev_get_drvdata(dev);
> +
> + up->is_suspending = true;
> +
> + return 0;
> +}
> +
> +static void serial_omap_complete(struct device *dev)
> +{
> + struct uart_omap_port *up = dev_get_drvdata(dev);
> +
> + up->is_suspending = false;
> +}
> +
> static int serial_omap_suspend(struct device *dev)
> {
> struct uart_omap_port *up = dev_get_drvdata(dev);
> @@ -1330,7 +1347,10 @@ static int serial_omap_resume(struct device *dev)
>
> return 0;
> }
> -#endif
> +#else
> +#define serial_omap_prepare NULL
> +#define serial_omap_prepare NULL
> +#endif /* CONFIG_PM_SLEEP */
>
> static void omap_serial_fill_features_erratas(struct uart_omap_port *up)
> {
> @@ -1616,6 +1636,10 @@ static int serial_omap_runtime_suspend(struct device *dev)
> struct uart_omap_port *up = dev_get_drvdata(dev);
> struct omap_uart_port_info *pdata = dev->platform_data;
>

I'd like to see a comment here about why we return error. It's written
in the changelog, but it deserves a comment here as well. Something like:

When using 'no_console_suspend', the console UART must not be suspended.
Since driver suspend is managed by runtime suspend, preventing runtime
suspend (by returning error) will keep device active during suspend.


> + if (up->is_suspending && !console_suspend_enabled
> + && uart_console(&up->port))

nit: can you put the '&&' at the end of the first line, and have the
2nd line line up with the start of the first line?

See other examples of similiar multi-line checks elsewhere in the
driver.

Other than those minor things, this patch is good.

Then, can you repost and break this into 2 series since they can go
independently.

Patches 1-2 need to go through the serial tree (Greg), and I will queue
up the OMAP specific changes once Greg has queued the serial core changes.

Kevin
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