On Thu, Dec 14 2023 at 09:54, xiongxin wrote:
> 在 2023/12/13 22:59, Thomas Gleixner 写道:
>> Did you actually look at the sequence I gave you?
>>
>> Suspend:
>>
>> i2c_hid_core_suspend()
>> disable_irq(); <- Marks it disabled and eventually
>> masks it.
>>
>> gpio_irq_suspend()
>> save_registers(); <- Saves masked interrupt
>>
>> Resume:
>>
>> gpio_irq_resume()
>> restore_registers(); <- Restores masked interrupt
>>
>> i2c_hid_core_resume()
>> enable_irq(); <- Unmasks interrupt and removes the
>> disabled marker
>>
>>
>> Have you verified that this order of invocations is what happens on
>> your machine?
>
> As described earlier, in the current situation, the irq_mask() callback
> of gpio irq_chip is called in mask_irq(), followed by the disable_irq()
> in i2c_hid_core_suspend(), unmask_irq() will not be executed.
Which is correct.
> Then call enable_irq() in i2c_hid_core_resume(). Since gpio irq_chip
> does not implement the irq_startup() callback, it ends up calling
> irq_enable().
>
> The irq_enable() function is then implemented as follows:
>
> irq_state_clr_disabled(desc);
> if (desc->irq_data.chip->irq_enable) {
> desc->irq_data.chip->irq_enable(&desc->irq_data);
> irq_state_clr_masked(desc);
> } else {
> unmask_irq(desc);
> }
>
> Because gpio irq_chip implements irq_enable(), unmask_irq() is not
> executed, and gpio irq_chip's irq_unmask() callback is not called.
> Instead, irq_state_clr_masked() was called to clear the masked flag.
>
> The irq masked behavior is actually controlled by the
> irq_mask()/irq_unmask() callback function pairs in gpio irq_chip. When
> the whole situation occurs, there is one more irq_mask() operation, or
> one less irq_unmask() operation. This ends the i2c hid resume and the
> gpio corresponding i2c hid interrupt is also masked.
>
> Please help confirm whether the current situation is a BUG, or suggest
> other solutions to fix it.
Again, I already explained to you in great detail why the core code is
correct and does not have a bug.
But as you insist that the bug is in the core code you obviously failed
to validate what I asked you to validate:
>> i2c_hid_core_resume()
>> enable_irq(); <- Unmasks interrupt and removes the
>> disabled marker
The keyword to validate here is 'Unmasks'.
As gpio_dwapb implements the irq_enable() callback enable_irq() is not
going to end up invoking the irq_unmask() callback. But the irq_enable()
callback is required to be a superset of irq_unmask(). I.e. the core
code expects it to do:
1) Some preparatory work to enable the interrupt line
2) Unmask the interrupt, which is why the masked state is cleared
by the core after invoking the irq_enable() callback.
which is pretty obvious because if an interrupt chip does not implement
the irq_enable() callback the core defaults to irq_unmask()
Correspondingly the core expects from the irq_disable() callback:
1) To mask the interrupt
2) To do some extra work to disable the interrupt line
which is obvious again because the core defaults to irq_mask() if the
irq_disable() callback is not implemented by the interrupt chip.
I'm pretty sure that with the previous provided information and the
extra information above you can figure out yourself that:
1) the core code is correct as is
2) where exactly the problem is located and how to fix it
No?
Thanks,
tglx
