From: Rob Herring <robh@kernel.org>
To: John Stultz <john.stultz@linaro.org>
Cc: lkml <linux-kernel@vger.kernel.org>,
Alexander Graf <agraf@suse.de>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Kevin Hilman <khilman@kernel.org>,
Ulf Hansson <ulf.hansson@linaro.org>, Pavel Machek <pavel@ucw.cz>,
Len Brown <len.brown@intel.com>, Todd Kjos <tkjos@google.com>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"open list:THERMAL" <linux-pm@vger.kernel.org>
Subject: Re: [RFC][PATCH] driver core: Extend returning EPROBE_DEFER for two minutes after late_initcall
Date: Thu, 13 Feb 2020 19:51:18 -0600 [thread overview]
Message-ID: <CAL_Jsq+P0FZU9DnRhgYu6kvCFVbia=Z20VWNR2qi-Zwv=YtQhQ@mail.gmail.com> (raw)
In-Reply-To: <20200214004413.12450-1-john.stultz@linaro.org>
On Thu, Feb 13, 2020 at 6:44 PM John Stultz <john.stultz@linaro.org> wrote:
>
> Due to commit e01afc3250255 ("PM / Domains: Stop deferring probe
> at the end of initcall"), along with commit 25b4e70dcce9
> ("driver core: allow stopping deferred probe after init") after
> late_initcall, drivers will stop getting EPROBE_DEFER, and
> instead see an error causing the driver to fail to load.
>
> That change causes trouble when trying to use many clk drivers
> as modules, as the clk modules may not load until much later
> after init has started. If a dependent driver loads and gets an
> error instead of EPROBE_DEFER, it won't try to reload later when
> the dependency is met, and will thus fail to load.
>
> Instead of reverting that patch, this patch tries to extend the
> time that EPROBE_DEFER is retruned by two minutes, to (hopefully)
> ensure that everything has had a chance to load.
I think regulators already has some delay like this. We should use the
same timeouts.
We also have the 'deferred_probe_timeout' cmdline option. It's deemed
a debug option currently, but we could change that and change the
default.
> Specifically, on db845c, this change allows us to set
> SDM_GPUCC_845, QCOM_CLK_RPMH and COMMON_CLK_QCOM as modules and
> get a working system, where as without it the display will fail
> to load.
>
> Cc: Alexander Graf <agraf@suse.de>
> Cc: Rob Herring <robh@kernel.org>
> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> Cc: Kevin Hilman <khilman@kernel.org>
> Cc: Ulf Hansson <ulf.hansson@linaro.org>
> Cc: Pavel Machek <pavel@ucw.cz>
> Cc: Len Brown <len.brown@intel.com>
> Cc: Todd Kjos <tkjos@google.com>
> Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: linux-pm@vger.kernel.org
> Fixes: e01afc3250255 ("PM / Domains: Stop deferring probe at the end of initcall")
> Fixes: 25b4e70dcce9 ("driver core: allow stopping deferred probe after init")
We can debate the design, but those work as designed. So Fixes?
> Signed-off-by: John Stultz <john.stultz@linaro.org>
> ---
> drivers/base/dd.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index b25bcab2a26b..35ebae8b65be 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -311,6 +311,12 @@ static void deferred_probe_timeout_work_func(struct work_struct *work)
> }
> static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
>
> +static void deferred_initcall_done_work_func(struct work_struct *work)
> +{
> + initcalls_done = true;
> +}
> +static DECLARE_DELAYED_WORK(deferred_initcall_done_work, deferred_initcall_done_work_func);
> +
> /**
> * deferred_probe_initcall() - Enable probing of deferred devices
> *
> @@ -327,7 +333,7 @@ static int deferred_probe_initcall(void)
> driver_deferred_probe_trigger();
> /* Sort as many dependencies as possible before exiting initcalls */
> flush_work(&deferred_probe_work);
> - initcalls_done = true;
> + schedule_delayed_work(&deferred_initcall_done_work, 120 * HZ);
>
> /*
> * Trigger deferred probe again, this time we won't defer anything
> --
> 2.17.1
>
next prev parent reply other threads:[~2020-02-14 1:51 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-14 0:44 [RFC][PATCH] driver core: Extend returning EPROBE_DEFER for two minutes after late_initcall John Stultz
2020-02-14 1:51 ` Rob Herring [this message]
2020-02-14 2:41 ` John Stultz
2020-02-15 21:26 ` Rob Herring
2020-02-14 2:19 ` Bjorn Andersson
2020-02-14 4:05 ` John Stultz
2020-02-14 5:15 ` Bjorn Andersson
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