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Re: [Question] about patch: don't use [delayed_]work_pending()

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Hello,

On Thu, Sep 01, 2016 at 05:09:36PM +0800, qiaozhou wrote:
> In our system, we do cpu clock init in of_clk_init path, and use pm qos to
> maintain cpu/cci clock. Firstly we init a CCI_CLK_QOS and set a default
> value, then update CCI_CLK_QOS to limit CCI min frequency according to
> current cpu frequency. Before calling pm_qos_update_request, irq is
> disabled, but after the calling, irq is enabled in cancel_delayed_work_sync,
> which causes some inconvenience before Before this patch is applied, it
> checks pending work and won't do cancel_delayed_work_sync in this boot up
> phase.

So, cancel_delayed_work_sync() usually shouldn't be called with irq
disabled as it's a possibly blocking call.

> The simple calling sequence is like this:
> 
> start_kernel -> of_clk_init -> cpu_clk_init -> pm_qos_add_request(xx,
> default_value),
> 
> then pm_qos_update_request.
> 
> I don't know whether it's meaningful to still check pending work here, or
> it's not suggested to use pm_qos_update_request in this early boot up phase.
> Could you help to share some opinions? (I can fix this issue by adding the
> current qos value directly instead of default value, though.)

Hmmm... but I suppose this is super-early in the boot.  Would it make
sense to have a static variable (e.g. bool clk_fully_initailized) to
gate the cancel_delayed_sync() call?

Thanks.

-- 
tejun

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[Question] about patch: don't use [delayed_]work_pending() qiaozhou <qiaozhou@asrmicro.com> - 2016-09-01 11:30 +0200
  Re: [Question] about patch: don't use [delayed_]work_pending() Tejun Heo <tj@kernel.org> - 2016-09-01 23:40 +0200
    Re: [Question] about patch: don't use [delayed_]work_pending() qiaozhou <qiaozhou@asrmicro.com> - 2016-09-02 03:20 +0200
      Re: [Question] about patch: don't use [delayed_]work_pending() Tejun Heo <tj@kernel.org> - 2016-09-02 16:00 +0200
        Re: [Question] about patch: don't use [delayed_]work_pending() Tejun Heo <tj@kernel.org> - 2016-09-02 16:30 +0200
          Re: [Question] about patch: don't use [delayed_]work_pending() qiaozhou <qiaozhou@asrmicro.com> - 2016-09-03 17:30 +0200
          Re: [Question] about patch: don't use [delayed_]work_pending() qiaozhou <qiaozhou@asrmicro.com> - 2016-09-05 07:40 +0200
            [PATCH] power: avoid calling cancel_delayed_work_sync() during early  boot Tejun Heo <tj@kernel.org> - 2016-09-05 14:40 +0200
              Re: [PATCH] power: avoid calling cancel_delayed_work_sync() during  early boot "Rafael J. Wysocki" <rafael@kernel.org> - 2016-09-05 15:00 +0200

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