Hi Daniel, On 07/09/2020 10:44, Andy Shevchenko wrote: > +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/ > I also like to use the NNTP interface on lore: nntp://nntp.lore.kernel.org That lets you read/reply to many of the kernel lists without actually having to subscribe. And of course gets the whole archive too. >> 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 > -- Regards -- Kieran
