+Cc: Surface community people. On Sat, Sep 05, 2020 at 09:19:51AM +0100, Daniel Scally wrote: > > 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. Use lore [5] and its feature of downloading mailbox (or just seeing Message-Id which is enough for good MUA to attach reply properly to the thread). [5]: https://lore.kernel.org/linux-media/12fbe3f5c6a16c5f3447adbc09fe27ceb2b16823.1589625807.git.mchehab+huawei@xxxxxxxxxx/ > 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. > [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 -- With Best Regards, Andy Shevchenko
