Hi, Thank you the response! My replies inline below... On Mon, April 15, 2024 11:14 am, Peter Robinson wrote: > Hi Derek, > >> I have a Wandboard (yeah, I know, OLD Hardware) currently running a > > As in the imx6 based Wandboard? Which model/rev? What release of > Fedora, what kernel etc? Yes, an imx6 Wandboard. I'll have to go upstairs and open the case to see the EXACT model/rev printed on the PCB. Running "cat /proc/cpuinfo" only shows a single core. And it's running Fedora 36, currently running 5.18.9-200.fc36.armv7hl and libgpiod-1.6.3-7.fc36.armv7hl >> project, and I'm trying to add some GPIO inputs to it. In previous GPIO >> handling (on a different platform) I used the /sys/class/gpio interfaces >> to set up the GPIO, but I've discovered this is now deprecated and >> removed >> from Fedora. So I installed libgpiod and am trying to use it. > > Yes, we stopped supporting that because it was deprecated and upstream > asked us to. > >> I'm using >> https://download.technexion.com/development_resources/wandboard/wbquad-revb1-userguide.pdf >> as a reference for the board layout. Specifically, on page 27, it shows >> me that the JP4 header connects to GPIO3_12, GPIO3_27, GPIO6_31, >> CPIO1_24, >> GPIO7_8, GPIO3_26, GPIO_18, and GPIO_19. >> >> I figure that GPIO_18 is going to be gpiochip0 line 18, and GPIO3_12 >> will >> be gpiochip3 line 12.. Except that gpiodetect only tells me I have >> gpiochip0 through gpiochip6, so I'm not sure where GPIO7_8 would get >> mapped. That's the first issue I have. > > You'd likely need to look at the device tree and pinmappings to see > how they're mapped out. I was trying to follow the device tree, and found a dts in the wandboard-org tree that seemed to match the settings from that PDF I pointed to. Of course, that may or may not be correct to the actual hardware I have running upstairs. >> The second issue is that the kernel does not have any named mappings, so >> running gpioinfo just displays generic data, like: >> >> gpiochip6 - 32 lines: >> line 0: unnamed unused input active-high >> line 1: unnamed unused input active-high >> >> Except, of course, looking at gpiochip3 line 12 shows me: >> >> gpiochip3 - 32 lines: >> ... >> line 12: unnamed "scl" output active-high [used >> open-drain] >> >> Which seems to imply that that GPIO3_12 is actually used for something >> else -- or my mapping strategy is off. > > Probably a kernel device, often GPIOs are used for other things. Being only ancillarily associated with Arm/Embedded HW -- what does it mean for a GPIO to be "used for other things"? And more importantly, why would it be wired to a header if it's being used for something else? > A quick look at the dtsi for the wandboards some of the GPIOs re used > for SCL/SDA pins on two of the i2c buses. The i2c1 seems to not have > anything attached so I guess in on a pin header for end user use, and > i2c12 has a audio codec and for the camera connector. How exactly is this done? Is the pin wired to two places on the PCB? >> I'd appreciate any guidance anyone might have on this subject. > > If it's a iMX6 based Wandboard the guidance will be limted as the > support for ARMv7 went EOL when F-36 did so I have no recollection of > what kernel, libgpiod version etc was shipped there. Understood. I just happen to have bought into the Wandboard platform a long time ago, so this is what I've been using for the project. It uses a USB Relay, leveraging CRelay, so theoretically I could swap the system out for a different board in order to get 4 GPIOs for external switch detction, but honestly I'd rather not spend the money... :) > Peter -derek -- Derek Atkins 617-623-3745 derek@xxxxxxxxx www.ihtfp.com Computer and Internet Security Consultant -- _______________________________________________ arm mailing list -- arm@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to arm-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/arm@xxxxxxxxxxxxxxxxxxxxxxx Do not reply to spam, report it: https://pagure.io/fedora-infrastructure/new_issue
