Hello Following on from this thread: https://www.spinics.net/lists/linux-driver-devel/msg135122.html - apologies, can't see a way to reply to it directly. Myself and others [1] have been trying to get cameras working on Microsoft Surface and similar platforms, currently I'm working on expanding Jordan's module connecting cameras to the cio2 infrastructure (which works - we can use it to take images), aiming to discover connection information from SSDB in the DSDT, as well as connect as many supported sensors as are found on the device. I'm just struggling with a problem I've encountered using the swnode patch that Heikki linked in that thread; the module's working ok when I only attempt to connect a single one of my sensors (by preventing the driver for the other sensor from loading, in which case this new module ignores the sensor), but when I attempt to connect both cameras at the same time I get a kernel oops as part of software_node_get_next_child. The module is creating software_nodes like this... /sys/kernel/software_node/INT343E/port0/endpoint0 /sys/kernel/software_node/INT343E/port1/endpoint0 /sys/kernel/software_node/OVTI2680/port0/endpoint0 /sys/kernel/software_node/OVTI5648/port0/endpoint0 And that's the structure that I expect to see, but it seems like the call to list_next_entry in that function is returning something that isn't quite a valid swnode. Printing the address of c->fwnode after that point returns "3", which isn't a valid address of course, and that's causing the oops when it's either returned (in the version of the function without the patches) or when the program flow tries to call the "get" op against that fwnode (in the patched version). I've been trying to track it down for a while now without success, so I posted the problem on SO[2] and it was suggested that I mail these addressees for advice - hope that that is ok. My copy of Jordan's module is parked in my git repo [3] for now, and requires a batch of patches from Jordan's repo [4] (one made by Heikki to fill in the missing swnode graph pieces, and some further tweaks) - I've been applying those against 5.8.0-rc7. Any other criticism more than welcome - I'm new to both c and kernel programming so I'm happy to take all the advice people have the time to give. On a more general note; Kieran from the libcamera project suggested we ought to be talking to you guys anyway to get some guidance on design, and some more expert eye on the things we don't really understand. In particular; we haven't been able to figure out how sensors that are intended to work with the cio2 ipu3 stuff have their clock/regulators supplied - in fact I can strip all the "usual" clock/regulator functionality out of my camera's driver and it still functions fine, which seems a bit weird. So far all we're doing as "power management" of the camera's is turning on the GPIO pins that DSDT tables assign to the tps68470 PMICs the cameras are theoretically hooked up to...but given the drivers continue to work without using the PMICs regulator and clk drivers (which we found in the intel-lts tree on Github), we're a bit confused exactly how these are connected. Given the potential for actual hardware damage if we mess something up there it'd be great if anyone can shed some light on those elements. Regards Dan [1] https://github.com/linux-surface/linux-surface/issues/91 [2] https://stackoverflow.com/questions/63742967/what-is-causing-this-kernel-oops-when-parsing-firmware? [3] https://github.com/djrscally/miix-510-cameras/blob/master/surface_camera/surface_camera.c [4] https://github.com/jhand2/surface-camera/tree/master/patches
