Messages in this thread | | | Subject | Re: [v2] i2c: mediatek: Move suspend and resume handling to NOIRQ phase | From | Grygorii Strashko <> | Date | Thu, 10 Dec 2020 15:03:52 +0200 |
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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?
Is "some device" in Kernel mainline?
> 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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