Created attachment 256667 [details] dmesg The HP x2 210 g2 tablet has two cameras: one facing the user (front) and one facing away (back). The front camera is detected as an HP TrueVision HD camera, but the back camera is not detected at all. The one clue I have as to where to start is that there is one multimedia device listed in lspci that is not associated with any kernel driver: 00:03.0 Multimedia controller: Intel Corporation Atom/Celeron/Pentium Processor x5-E8000/J3xxx/N3xxx Series Imaging Unit (rev 36) Subsystem: Hewlett-Packard Company Atom/Celeron/Pentium Processor x5-E8000/J3xxx/N3xxx Series Imaging Unit Flags: fast devsel, IRQ 255 Memory at 91000000 (32-bit, non-prefetchable) [disabled] [size=4M] Capabilities: [80] Power Management version 2 Capabilities: [90] MSI: Enable- Count=1/1 Maskable- 64bit- dmesg is attached. Is there anything else I could do to debug this issue?
Ah, I figured it out by looking at the ACPI tables (https://bugzilla.kernel.org/attachment.cgi?id=256669). The back camera is an Intel AVStream 2401 camera, which should be handled by the INTEL_ATOMISP driver. It uses OV8858, OV5670 (OmniVision) and/or GC2235 (GalaxyCore) sensors, as shown in DSDT. However, the driver does not seem to bind to the device. If I modprobe it, the gcc2235 module gets loaded as well, but lspci still does not show any driver in use. It's not a problem of firmware, either, since the kernel log does not show that any firmware was requested to begin with.