1. 12 11月, 2014 1 次提交
    • U
      PM / Domains: Fix initial default state of the need_restore flag · 67732cd3
      Ulf Hansson 提交于
      The initial state of the device's need_restore flag should'nt depend on
      the current state of the PM domain. For example it should be perfectly
      valid to attach an inactive device to a powered PM domain.
      
      The pm_genpd_dev_need_restore() API allow us to update the need_restore
      flag to somewhat cope with such scenarios. Typically that should have
      been done from drivers/buses ->probe() since it's those that put the
      requirements on the value of the need_restore flag.
      
      Until recently, the Exynos SOCs were the only user of the
      pm_genpd_dev_need_restore() API, though invoking it from a centralized
      location while adding devices to their PM domains.
      
      Due to that Exynos now have swithed to the generic OF-based PM domain
      look-up, it's no longer possible to invoke the API from a centralized
      location. The reason is because devices are now added to their PM
      domains during the probe sequence.
      
      Commit "ARM: exynos: Move to generic PM domain DT bindings"
      did the switch for Exynos to the generic OF-based PM domain look-up,
      but it also removed the call to pm_genpd_dev_need_restore(). This
      caused a regression for some of the Exynos drivers.
      
      To handle things more properly in the generic PM domain, let's change
      the default initial value of the need_restore flag to reflect that the
      state is unknown. As soon as some of the runtime PM callbacks gets
      invoked, update the initial value accordingly.
      
      Moreover, since the generic PM domain is verifying that all devices
      are both runtime PM enabled and suspended, using pm_runtime_suspended()
      while pm_genpd_poweroff() is invoked from the scheduled work, we can be
      sure of that the PM domain won't be powering off while having active
      devices.
      
      Do note that, the generic PM domain can still only know about active
      devices which has been activated through invoking its runtime PM resume
      callback. In other words, buses/drivers using pm_runtime_set_active()
      during ->probe() will still suffer from a race condition, potentially
      probing a device without having its PM domain being powered. That issue
      will have to be solved using a different approach.
      
      This a log from the boot regression for Exynos5, which is being fixed in
      this patch.
      
      ------------[ cut here ]------------
      WARNING: CPU: 0 PID: 308 at ../drivers/clk/clk.c:851 clk_disable+0x24/0x30()
      Modules linked in:
      CPU: 0 PID: 308 Comm: kworker/0:1 Not tainted 3.18.0-rc3-00569-gbd9449f-dirty #10
      Workqueue: pm pm_runtime_work
      [<c0013c64>] (unwind_backtrace) from [<c0010dec>] (show_stack+0x10/0x14)
      [<c0010dec>] (show_stack) from [<c03ee4cc>] (dump_stack+0x70/0xbc)
      [<c03ee4cc>] (dump_stack) from [<c0020d34>] (warn_slowpath_common+0x64/0x88)
      [<c0020d34>] (warn_slowpath_common) from [<c0020d74>] (warn_slowpath_null+0x1c/0x24)
      [<c0020d74>] (warn_slowpath_null) from [<c03107b0>] (clk_disable+0x24/0x30)
      [<c03107b0>] (clk_disable) from [<c02cc834>] (gsc_runtime_suspend+0x128/0x160)
      [<c02cc834>] (gsc_runtime_suspend) from [<c0249024>] (pm_generic_runtime_suspend+0x2c/0x38)
      [<c0249024>] (pm_generic_runtime_suspend) from [<c024f44c>] (pm_genpd_default_save_state+0x2c/0x8c)
      [<c024f44c>] (pm_genpd_default_save_state) from [<c024ff2c>] (pm_genpd_poweroff+0x224/0x3ec)
      [<c024ff2c>] (pm_genpd_poweroff) from [<c02501b4>] (pm_genpd_runtime_suspend+0x9c/0xcc)
      [<c02501b4>] (pm_genpd_runtime_suspend) from [<c024a4f8>] (__rpm_callback+0x2c/0x60)
      [<c024a4f8>] (__rpm_callback) from [<c024a54c>] (rpm_callback+0x20/0x74)
      [<c024a54c>] (rpm_callback) from [<c024a930>] (rpm_suspend+0xd4/0x43c)
      [<c024a930>] (rpm_suspend) from [<c024bbcc>] (pm_runtime_work+0x80/0x90)
      [<c024bbcc>] (pm_runtime_work) from [<c0032a9c>] (process_one_work+0x12c/0x314)
      [<c0032a9c>] (process_one_work) from [<c0032cf4>] (worker_thread+0x3c/0x4b0)
      [<c0032cf4>] (worker_thread) from [<c003747c>] (kthread+0xcc/0xe8)
      [<c003747c>] (kthread) from [<c000e738>] (ret_from_fork+0x14/0x3c)
      ---[ end trace 40cd58bcd6988f12 ]---
      
      Fixes: a4a8c2c4 (ARM: exynos: Move to generic PM domain DT bindings)
      Reported-and-tested0by: Sylwester Nawrocki <s.nawrocki@samsung.com>
      Reviewed-by: NSylwester Nawrocki <s.nawrocki@samsung.com>
      Reviewed-by: NKevin Hilman <khilman@linaro.org>
      Signed-off-by: NUlf Hansson <ulf.hansson@linaro.org>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      67732cd3
  2. 08 11月, 2014 1 次提交
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  5. 31 10月, 2014 21 次提交