Messages in this thread | | | Subject | Re: [PATCH v1] gpio: dwapb: mask/unmask IRQ when disable/enable it | From | luojiaxing <> | Date | Mon, 7 Dec 2020 20:44:55 +0800 |
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On 2020/12/6 6:15, Serge Semin wrote: > On Tue, Dec 01, 2020 at 04:59:21PM +0800, luojiaxing wrote: >> 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. >> > Hmm, that sounds like a problem, but the explanation is a bit unclear > to me. AFAICS you are saying that the only callbacks which are > called during the IRQ request/release are the irq_enable(), right?
Yes, but one point needs to be clarified, for IRQ requests, it calls irq_enable(); for IRQ release, it calls irq_disable().
Actually I am thinking that why only irq_enable()/irq_disable() is called since the mask and enable flags of irq_data are both set.
Does IRQ subsystem expect irq_enable to set both mask and enable? If we didn't do that, the state machine of the software is different from hardware, at least for mask bit.
> If > so then the only reason why we haven't got a problem reported due to > that so far is that the IRQs actually unmasked by default.
yes, I think so, Common drivers do not mask the IRQ before releasing it. But that's possible.
> > In anyway I'd suggest to join someone from the kernel IRQs-related > subsystem to this discussion to ask their opinion whether the IRQs > setup procedure is supposed to work like you say and the irq_enable > shall actually also unmask IRQs. > > Thomas, Jason, Mark, could you give us your comment about the issue? > > -Sergey > >> >> > . >
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