Hello, [dropped Alexandru Tachici from Cc:, the address bounces] On Sun, Oct 27, 2024 at 11:54:09AM +0000, Jonathan Cameron wrote: > On Thu, 24 Oct 2024 19:17:03 +0200 > Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxx> wrote: > > > For the AD7124 chip the logical irq line (̅R̅D̅Y) is physically on the same > > pin as the spi MISO output (DOUT) and so reading a register might > > trigger an interrupt. For correct operation it's critical that the > > actual state of the pin can be read to judge if an interrupt event is a > > real one or just a spurious one triggered by toggling the line in its > > MISO mode. > > This text should note that this is a limitation with the interrupt controller. > The IRQ is disabled when those reads are going on, yet the controller is > still detecting the interrupt and reporting it on reenable. > I'm not an expert in what the kernel IRQ subsystem requires so maybe > this is a valid implementation. This is even the saner option and a controller not triggering might miss irqs. Consider the process that triggered a conversion and then calls enable_irq() is preempted long enough that the conversion is already done when enable_irq() is called. The completion would just time out and no measurement reported. > > Allow specification of an "interrupt-gpios" property instead of a plain > > interrupt. The semantic is that the GPIO's interrupt is to be used as > > event source and reading the GPIO can be used to differentiate between a > > real event and one triggered by MISO. > > This sort of hack is a bit nasty and if we are going to do it we should > allow for double wiring - so to separate GPIO and interrupt pins on the > host wired to single pin on the device. > > The binding does that by allowing both interrupts and interrupt-gpio > but we need to make that explicit in this text. Arguably even when > they are the same pin the binding should treat them as independent > and the driver should get the gpio from one, and the interrupt from > the other. This would also need a code update because currently the interrupt-gpio is only used if no interrupt is specified. > I also definitely need input from Analog Devices folk on this series. Good candidates to comment are still on Cc: Best regards Uwe
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