[PATCH 5/7] serial: omap: Fix PM regression with deferred probe for pm_runtime_reinit

[Ulf Hansson]

On 11 February 2016 at 00:02, Tony Lindgren <tony at atomide.com> wrote:
> Commit 5de85b9d57ab ("PM / runtime: Re-init runtime PM states at probe
> error and driver unbind") introduced pm_runtime_reinit() that is used
> to reinitialize PM runtime after -EPROBE_DEFER. This allows shutting
> down the device after a failed probe.
>
> However, for drivers using pm_runtime_use_autosuspend() this can cause
> a state where suspend callback is never called after -EPROBE_DEFER.
> On the following device driver probe, hardware state is different from
> the PM runtime state causing omap_device to produce the following
> error:
>
> omap_device_enable() called from invalid state 1
>
> And with omap_device and omap hardware being picky for PM, this will
> block any deeper idle states in hardware.
>
> The solution is to fix the drivers to follow the PM runtime documentation:
>
> 1. For sections of code that needs the device disabled, use
>    pm_runtime_put_sync_suspend() if pm_runtime_set_autosuspend() has
>    been set.
>
> 2. For driver exit code, use pm_runtime_dont_use_autosuspend() before
>    pm_runtime_put_sync() if pm_runtime_use_autosuspend() has been
>    set.
>
> Fixes: 5de85b9d57ab ("PM / runtime: Re-init runtime PM states at probe
> error and driver unbind")
> Cc: linux-serial at vger.kernel.org
> Cc: Alan Stern <stern at rowland.harvard.edu>
> Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
> Cc: Kevin Hilman <khilman at baylibre.com>
> Cc: Nishanth Menon <nm at ti.com>
> Cc: Rafael J. Wysocki <rafael at kernel.org>
> Cc: Ulf Hansson <ulf.hansson at linaro.org>
> Cc: Tero Kristo <t-kristo at ti.com>
> Signed-off-by: Tony Lindgren <tony at atomide.com>

Acked-by: Ulf Hansson <ulf.hansson at linaro.org>

Kind regards
Uffe


> ---
>
> Greg & Peter, I'd like to merge this along with other related fixes
> via the ARM SoC tree if no objections, please review and ack if
> this look OK to you.
>
> ---
>  drivers/tty/serial/omap-serial.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
> index b645f92..5c43f75 100644
> --- a/drivers/tty/serial/omap-serial.c
> +++ b/drivers/tty/serial/omap-serial.c
> @@ -1708,7 +1708,8 @@ static int serial_omap_probe(struct platform_device *pdev)
>         return 0;
>
>  err_add_port:
> -       pm_runtime_put(&pdev->dev);
> +       pm_runtime_dont_use_autosuspend(&pdev->dev);
> +       pm_runtime_put_sync(&pdev->dev);
>         pm_runtime_disable(&pdev->dev);
>         pm_qos_remove_request(&up->pm_qos_request);
>         device_init_wakeup(up->dev, false);
> @@ -1721,6 +1722,7 @@ static int serial_omap_remove(struct platform_device *dev)
>  {
>         struct uart_omap_port *up = platform_get_drvdata(dev);
>
> +       pm_runtime_dont_use_autosuspend(up->dev);
>         pm_runtime_put_sync(up->dev);
>         pm_runtime_disable(up->dev);
>         uart_remove_one_port(&serial_omap_reg, &up->port);
> --
> 2.7.0
>