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SubjectRe: [PATCH v2] driver core: Extend returning EPROBE_DEFER for two minutes after late_initcall
On Fri 14 Feb 15:32 PST 2020, John Stultz 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 30 seconds, to (hopefully)
> ensure that everything has had a chance to load.
>
> 30 seconds was chosen to match the similar timeout used by the
> regulator code here in commit 55576cf18537 ("regulator: Defer
> init completion for a while after late_initcall")
>
> 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.
>

With the $subject adjustment

Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>

Regards,
Bjorn

> 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")
> Signed-off-by: John Stultz <john.stultz@linaro.org>
> ---
> v2:
> * Add calls to driver_deferred_probe_trigger() after the two minute timeout,
> as suggested by Bjorn
> * Minor whitespace cleanups
> * Switch to 30 second timeout to match what the regulator code is doing as
> suggested by Rob.
> ---
> drivers/base/dd.c | 12 +++++++++++-
> 1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index d811e60610d3..0f519ef3b257 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -311,6 +311,15 @@ 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;
> + driver_deferred_probe_trigger();
> + flush_work(&deferred_probe_work);
> +}
> +static DECLARE_DELAYED_WORK(deferred_initcall_done_work,
> + deferred_initcall_done_work_func);
> +
> /**
> * deferred_probe_initcall() - Enable probing of deferred devices
> *
> @@ -327,7 +336,8 @@ 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,
> + msecs_to_jiffies(30000));
>
> /*
> * Trigger deferred probe again, this time we won't defer anything
> --
> 2.17.1
>

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