From mboxrd@z Thu Jan 1 00:00:00 1970 From: hkallweit1@gmail.com (Heiner Kallweit) Date: Tue, 25 Apr 2017 23:28:30 +0200 Subject: Status of Meson GPIO IRQ support In-Reply-To: <1489564235.25254.5.camel@baylibre.com> References: <1489564235.25254.5.camel@baylibre.com> Message-ID: To: linus-amlogic@lists.infradead.org List-Id: linus-amlogic.lists.infradead.org Am 15.03.2017 um 08:50 schrieb Jerome Brunet: > On Tue, 2017-03-14 at 21:41 +0100, Heiner Kallweit wrote: >> Jerome, >> >> when working on Meson I2C driver I was testing with a device where I wanted >> to use a GPIO as interrupt source. >> This isn't supported yet and when checking I found that end of last year >> you submitted related patches. After some intense discussions I found no >> further update. >> Was this topic put on-hold due to bigger technical issues? >> > > Well, the proposed code does work but, as you have probaly seen for yourself, > the maintainers of irqchip and gpio raised valid concerns, mainly about the way > the mapping is created in the gpio driver. Ideally, the mapping should be > created at probe time but, with a hierarchic interrupt domain, that means > allocating the parent irq. We only have 8 of those for 100+ gpios. > > I'm still not sure how to address the problem to be honest: Is there a way to > create mapping in hierarchy domain and allocate the parent only when the irq is > actually requested ? Or should we simply not use a hierarchy domain for this > controller (which seems to make sense) ? > Meanwhile I became somewhat familiar with the irq subsystem and do some tests with a GPIO IRQ driver based on GPIOLIB_IRQCHIP (in generic chained mode). This basically works, however I have a problem with edge detection. Level changes are not reliably detected. If I connect an input pin (configured for edge irq generation) to a output pin and change the value of the output pin no edge is detected. However if I use a cable to connect the input pin to VCC/GND manually then most of the time edges are detected (not always). Did you ever come across a similar problem during your tests? Regards, Heiner > I still hope to be able to do something on this topic but probably not tomorrow > :( Of course, If you have some spare time and want to contribute on this topic, > you are welcome to do so. > >> Rgds, Heiner > > Cheers > > Jerome >