Re: [PATCH] PM / Domains: Return -EPROBE_DEFER if we fail to init or turn-on domain

[Jon Hunter <jonathanh@nvidia.com>]

Ugh ... forgot to mark this as a V2! Will resend for clarity ...

On 31/07/15 10:16, Jon Hunter wrote:
> When a device is probed, the function dev_pm_domain_attach() is called
> to see if there is a power-domain that is associated with the device and
> needs to be turned on. If dev_pm_domain_attach() does not return
> -EPROBE_DEFER then the device will be probed.
> 
> For devices using genpd, dev_pm_domain_attach() will call
> genpd_dev_pm_attach(). If genpd_dev_pm_attach() does not find a power
> domain associated with the device then it returns an error code not
> equal to -EPROBE_DEFER to allow the device to be probed. However, if
> genpd_dev_pm_attach() does find a power-domain that is associated with
> the device, then it does not return -EPROBE_DEFER on failure and hence
> the device will still be probed. Furthermore, genpd_dev_pm_attach() does
> not check the error code returned by pm_genpd_poweron() to see if the
> power-domain was turned on successfully.
> 
> Fix this by checking the return code from pm_genpd_poweron() and
> returning -EPROBE_DEFER from genpd_dev_pm_attach on failure, if there
> is a power-domain associated with the device.
> 
> Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
> Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
> Acked-by: Kevin Hilman <khilman@linaro.org>
> ---
>  drivers/base/power/domain.c | 14 +++++++++-----
>  1 file changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index a1abe16dfe16..7666a1cbaf95 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -1947,7 +1947,10 @@ static void genpd_dev_pm_sync(struct device *dev)
>   * Both generic and legacy Samsung-specific DT bindings are supported to keep
>   * backwards compatibility with existing DTBs.
>   *
> - * Returns 0 on successfully attached PM domain or negative error code.
> + * Returns 0 on successfully attached PM domain or negative error code. Note
> + * that if a power-domain exists for the device, but it cannot be found or
> + * turned on, then return -EPROBE_DEFER to ensure that the device is not
> + * probed and to re-try again later.
>   */
>  int genpd_dev_pm_attach(struct device *dev)
>  {
> @@ -1984,7 +1987,7 @@ int genpd_dev_pm_attach(struct device *dev)
>  		dev_dbg(dev, "%s() failed to find PM domain: %ld\n",
>  			__func__, PTR_ERR(pd));
>  		of_node_put(dev->of_node);
> -		return PTR_ERR(pd);
> +		return -EPROBE_DEFER;
>  	}
>  
>  	dev_dbg(dev, "adding to PM domain %s\n", pd->name);
> @@ -2002,14 +2005,15 @@ int genpd_dev_pm_attach(struct device *dev)
>  		dev_err(dev, "failed to add to PM domain %s: %d",
>  			pd->name, ret);
>  		of_node_put(dev->of_node);
> -		return ret;
> +		goto out;
>  	}
>  
>  	dev->pm_domain->detach = genpd_dev_pm_detach;
>  	dev->pm_domain->sync = genpd_dev_pm_sync;
> -	pm_genpd_poweron(pd);
> +	ret = pm_genpd_poweron(pd);
>  
> -	return 0;
> +out:
> +	return ret ? -EPROBE_DEFER : 0;
>  }
>  EXPORT_SYMBOL_GPL(genpd_dev_pm_attach);
>  #endif /* CONFIG_PM_GENERIC_DOMAINS_OF */
> 

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