On Mon, Mar 19, 2018 at 11:05:19AM +0100, Uwe Kleine-König wrote: > Hello, > > this is a set of patches I created while I tried to understand how DSA > works. I don't claim I already got there and so the first 3 fixes are > trivial only. > > I tried to make the switch on the espressobin SBC use the interrupt line > and needed the fourth patch to make this work. Given I don't have access > to the documentation of the Marvell switch, the patch is probably not > correct though (and so doesn't have a S-o-b). > > When I first added the irq as: > > interrupt-parent = <&gpiosb>; > interrupts = <23 IRQ_TYPE_LEVEL_LOW>; > > to the switch of the espressobin's dtb, the irq couldn't be used. The > reason is the interaction of several things: > > - On the first try to probe the switch, the driver did: > > irq = of_irq_get(np, 0); > request_threaded_irq(irq, NULL, func, IRQF_ONESHOT | > IRQF_TRIGGER_FALLING, ...); > > and then later aborted with -EPROBE_DEFER because another resource > wasn't available yet. This correctly undid the request_threaded_irq > above using free_irq. > > - When the probe routine was entered again, the call to of_irq_get(np, 0) > failed becauce the irq code remembered that the irq was requested > using edge triggered logic with: > > irq: type mismatch, failed to map hwirq-23 for gpio! > > (kernel/irq/irqdomain.c, line 801) > > Any of the following changes would make the problem disappear: > > - use IRQ_TYPE_EDGE_FALLING in the device tree; > - drop IRQF_TRIGGER_FALLING from the driver's use of > request_threaded_irq() (I think, see below); and > - make the irq code forget the trigger type when the last action is > removed
Hi Uwe I think the correct fix here is to use the flag in device tree when requesting the interrupt. If it says IRQ_TYPE_LEVEL_LOW, then request it active low. Thinking about the hardware, active low is probably right, not edge. It will stay low until all the sources of interrupts are cleared. Andrew
