[PATCH 6/7] ARM: OMAP2+: Improve omap_device error for driver writers

[Ulf Hansson]

On 11 February 2016 at 00:02, Tony Lindgren <tony at atomide.com> wrote:
> Drivers using pm_runtime_use_autosuspend() may not get disabled 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.
>
> Let's add a proper error message so driver writers can easily fix
> their drivers for PM.
>
> In general, 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.
>
> Let's not return with 0 from _od_runtime_resume() as that will
> eventually lead into new drivers with broken PM runtime that will
> block deeper idle states on omaps.
>
> Cc: Alan Stern <stern at rowland.harvard.edu>
> 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


> ---
>  arch/arm/mach-omap2/omap_device.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/mach-omap2/omap_device.c b/arch/arm/mach-omap2/omap_device.c
> index 0437537..ebd8369 100644
> --- a/arch/arm/mach-omap2/omap_device.c
> +++ b/arch/arm/mach-omap2/omap_device.c
> @@ -602,8 +602,10 @@ static int _od_runtime_resume(struct device *dev)
>         int ret;
>
>         ret = omap_device_enable(pdev);
> -       if (ret)
> +       if (ret) {
> +               dev_err(dev, "use pm_runtime_put_sync_suspend() in driver?\n");
>                 return ret;
> +       }
>
>         return pm_generic_runtime_resume(dev);
>  }
> --
> 2.7.0
>