Messages in this thread | | | Subject | Re: [v2] i2c: mediatek: Move suspend and resume handling to NOIRQ phase | From | Grygorii Strashko <> | Date | Mon, 14 Dec 2020 22:08:16 +0200 |
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On 14/12/2020 10:48, Qii Wang wrote: > On Thu, 2020-12-10 at 15:03 +0200, Grygorii Strashko wrote: >> >> On 10/12/2020 03:56, Qii Wang wrote: >>> On Mon, 2020-12-07 at 18:35 +0200, Grygorii Strashko wrote: >>>> >>>>> >>>>> On Thu, 2020-12-03 at 10:01 +0200, Grygorii Strashko wrote: >>>>>> >>>>>> On 03/12/2020 03:25, Qii Wang wrote: >>>>>>> On Wed, 2020-12-02 at 16:35 +0100, Wolfram Sang wrote: >>>>>>>> Hi, >>>>>>>> >>>>>>>>> Some i2c device driver indirectly uses I2C driver when it is now >>>>>>>>> being suspended. The i2c devices driver is suspended during the >>>>>>>>> NOIRQ phase and this cannot be changed due to other dependencies. >>>>>>>>> Therefore, we also need to move the suspend handling for the I2C >>>>>>>>> controller driver to the NOIRQ phase as well. >>>>>>>>> >>>>>>>>> Signed-off-by: Qii Wang <qii.wang@mediatek.com> >>>>>>>> >>>>>>>> Is this a bugfix and should go into 5.10? Or can it wait for 5.11? >>>>>>>> >>>>>>> >>>>>>> Yes, Can you help to apply it into 5.10? Thanks >>>>>> >>>>>> To be honest if you still do have any i2c device which accessing i2c buss after _noirq >>>>>> stage and your driver does not implement .master_xfer_atomic() - you definitely have a bigger problem. >>>>>> So adding IRQF_NO_SUSPEND sound like a hack and probably works just by luck. >>>>>> >>>>> >>>>> At present, it is only a problem caused by missing interrupts, >>>>> and .master_xfer_atomic() just a implement in polling mode. Why not set >>>>> the interrupt to a state that can always be triggered? >>>>> >>>>> >>>> >>>> Because you must not use any IRQ driven operations after _noirq suspend state as it might (and most probably will) >>>> cause unpredictable behavior later in suspend_enter(): >>>> >>>> arch_suspend_disable_irqs(); >>>> BUG_ON(!irqs_disabled()); >>>> ^after this point any IRQ driven I2C transfer will cause IRQ to be re-enabled >>>> >>>> if you need turn off device from platform callbacks - .master_xfer_atomic() has to be implemented and used. >>>> >>> Maybe my comment is a bit disturbing.Our purpose is not to call i2c and >>> use interrupts after _noirq pauses.So We use >>> i2c_mark_adapter_suspended&i2c_mark_adapter_resumed to block these i2c >>> transfers, There will not have any IRQ driven I2C transfer after this >>> point: >>> arch_suspend_disable_irqs(); >>> BUG_ON(!irqs_disabled()); >>> But some device driver will do i2c transfer after >>> dpm_noirq_resume_devices in dpm_resume_noirq(PMSG_RESUME) when our >>> driver irq hasn't resume. >>> void dpm_resume_noirq(pm_message_t state) >>> { >>> dpm_noirq_resume_devices(state); >> >> Just to clarify. You have resume sequence in dpm_noirq_resume_devices >> dpm_noirq_resume_devices -> resume I2C -> resume some device -> do i2c transfer after? >> > > Yes.
huh. First consider IRQF_EARLY_RESUME - it's better, but still will be a hack
> >> Is "some device" in Kernel mainline? >> > > The problematic device driver is drivers/regulator/da9211-regulator.c in > Kernel mainline.
regulator is passive device, somebody should call it !?
And da9211-regulator IRQ handler should remain disabled till resume_device_irqs() call.
note. regulator_class implements only
static const struct dev_pm_ops __maybe_unused regulator_pm_ops = { .suspend = regulator_suspend, .resume = regulator_resume, };
> >>> resume_device_irqs(); >>> device_wakeup_disarm_wake_irqs(); >>> cpuidle_resume(); >>> } >>> .master_xfer_atomic() seems to be invalid for this question at this >>> time? >>> >> >
-- Best regards, grygorii
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