linux-kernel - Re: [PATCH v4 6/6] PM / Domains: Stop deferring probe at the end of initcall

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Date:   Tue, 10 Jul 2018 00:49:03 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Rob Herring <robh@...nel.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Alexander Graf <agraf@...e.de>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Kevin Hilman <khilman@...nel.org>,
        Joerg Roedel <joro@...tes.org>,
        Robin Murphy <robin.murphy@....com>,
        Mark Brown <broonie@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        devicetree@...r.kernel.org, boot-architecture@...ts.linaro.org,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>,
        Linux PM <linux-pm@...r.kernel.org>
Subject: Re: [PATCH v4 6/6] PM / Domains: Stop deferring probe at the end of initcall

On 9 July 2018 at 17:41, Rob Herring <robh@...nel.org> wrote:
> All PM domain drivers must be built-in (at least those using DT), so
> there is no point deferring probe after initcalls are done. Continuing
> to defer probe may prevent booting successfully even if managing PM
> domains is not required. This can happen if the user failed to enable
> the driver or if power-domains are added to a platform's DT, but there
> is not yet a driver (e.g. a new DTB with an old kernel).
>
> Call the driver core function driver_deferred_probe_check_init_done()
> instead of just returning -EPROBE_DEFER to stop deferring probe when
> initcalls are done.
>
> Acked-by: "Rafael J. Wysocki" <rjw@...ysocki.net>
> Cc: Kevin Hilman <khilman@...nel.org>
> Cc: Ulf Hansson <ulf.hansson@...aro.org>
> Cc: Pavel Machek <pavel@....cz>
> Cc: Len Brown <len.brown@...el.com>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: linux-pm@...r.kernel.org
> Signed-off-by: Rob Herring <robh@...nel.org>
> ---
> v4:
>  - Add Rafael's ack
>
> v3:
>   - Update to new function name
>
>  drivers/base/power/domain.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index 4925af5c4cf0..8c12213875c6 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -2253,7 +2253,7 @@ static int __genpd_dev_pm_attach(struct device *dev, struct device_node *np,
>                 mutex_unlock(&gpd_list_lock);
>                 dev_dbg(dev, "%s() failed to find PM domain: %ld\n",
>                         __func__, PTR_ERR(pd));
> -               return -EPROBE_DEFER;
> +               return driver_deferred_probe_check_state(dev);
>         }

This isn't the only error path where -EPROBE_DEFER may be returned
during attach in genpd.

Have a look at the callers of __genpd_dev_pm_attach() and also have a
second look inside __genpd_dev_pm_attach() itself. And in Rafael's
tree.

>
>         dev_dbg(dev, "adding to PM domain %s\n", pd->name);
> --
> 2.17.1

Besides the above, I am fine with the approach as such.

Kind regards
Uffe