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SubjectRe: [PATCH v1] gpio: dwapb: mask/unmask IRQ when disable/enable it
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On 2020/11/30 19:22, Andy Shevchenko wrote:
> On Mon, Nov 30, 2020 at 05:36:19PM +0800, Luo Jiaxing wrote:
>> The mask and unmask registers are not configured in dwapb_irq_enable() and
>> dwapb_irq_disable(). In the following situations, the IRQ will be masked by
>> default after the IRQ is enabled:
>>
>> mask IRQ -> disable IRQ -> enable IRQ
>>
>> In this case, the IRQ status of GPIO controller is inconsistent with it's
>> irq_data too. For example, in __irq_enable(), IRQD_IRQ_DISABLED and
>> IRQD_IRQ_MASKED are both clear, but GPIO controller do not perform unmask.
> Sounds a bit like a papering over the issue which is slightly different.
> Can you elaborate more, why ->irq_mask() / ->irq_unmask() are not being called?


Sure, The basic software invoking process is as follows:

Release IRQ:
free_irq() -> __free_irq() -> irq_shutdown() ->__irq_disable()

Disable IRQ:
disable_irq() -> __disable_irq_nosync() -> __disable_irq -> irq_disable
-> __irq_disable()

As shown before, both will call __irq_disable(). The code of it is as
follows:

if (irqd_irq_disabled(&desc->irq_data)) {
    if (mask)
        mask_irq(desc);

} else {
        irq_state_set_disabled(desc);
            if (desc->irq_data.chip->irq_disable) {
desc->irq_data.chip->irq_disable(&desc->irq_data);
                irq_state_set_masked(desc);
            } else if (mask) {
                mask_irq(desc);
    }
}

Because gpio-dwapb.c provides the hook function of irq_disable,
__irq_disable() will directly calls chip->irq_disable() instead of
mask_irq().

For irq_enable(), it's similar and the code is as follows:

if (!irqd_irq_disabled(&desc->irq_data)) {
    unmask_irq(desc);
} else {
    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);
    }
}

Similarly, because gpio-dwapb.c provides the hook function of
irq_enable, irq_enable() will directly calls chip->irq_enable() but does
not call unmask_irq().


Therefore, the current handle is as follows:

API of IRQ:        |   mask_irq()             | disable_irq()           
|    enable_irq()

gpio-dwapb.c:  |   chip->irq_mask()   | chip->irq_diable()   |   
chip->irq_enable()

I do not know why irq_enable() only calls chip->irq_enable(). However,
the code shows that irq_enable() clears the disable and masked flags in
the irq_data state.

Therefore, for gpio-dwapb.c, I thinks ->irq_enable also needs to clear
the disable and masked flags in the hardware register.




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