Hi Patrik, (CC'ing Sakari Ailus) On Sat, Apr 18, 2020 at 04:39:25PM +0200, Patrik Gfeller wrote: > Hello Mauro et al, > > I've recently switched to Linux, and I'm very impressed. Almost > everything thing works out of the box. Only the webcam on my device does > not. I did some digging and if I'm right an atomisp driver would be > required. Is this correct? Below the output of lspci: > > 00:00.0 Host bridge: Intel Corporation Atom/Celeron/Pentium Processor x5-E8000/J3xxx/N3xxx Series SoC Transaction Register (rev 36) > 00:02.0 VGA compatible controller: Intel Corporation Atom/Celeron/Pentium Processor x5-E8000/J3xxx/N3xxx Integrated Graphics Controller (rev 36) > 00:03.0 Multimedia controller: Intel Corporation Atom/Celeron/Pentium Processor x5-E8000/J3xxx/N3xxx Series Imaging Unit (rev 36) > 00:0a.0 Non-VGA unclassified device: Intel Corporation Device 22d8 (rev 36) > 00:0b.0 Signal processing controller: Intel Corporation Atom/Celeron/Pentium Processor x5-E8000/J3xxx/N3xxx Series Power Management Controller (rev 36) > 00:14.0 USB controller: Intel Corporation Atom/Celeron/Pentium Processor x5-E8000/J3xxx/N3xxx Series USB xHCI Controller (rev 36) > 00:1a.0 Encryption controller: Intel Corporation Atom/Celeron/Pentium Processor x5-E8000/J3xxx/N3xxx Series Trusted Execution Engine (rev 36) > 00:1c.0 PCI bridge: Intel Corporation Atom/Celeron/Pentium Processor x5-E8000/J3xxx/N3xxx Series PCI Express Port #1 (rev 36) > 00:1f.0 ISA bridge: Intel Corporation Atom/Celeron/Pentium Processor x5-E8000/J3xxx/N3xxx Series PCU (rev 36) > 01:00.0 Network controller: Qualcomm Atheros QCA9377 802.11ac Wireless Network Adapter (rev 31) > > According to the history it looks like the driver was removed from the > kernel in 2018 and replaced with a dummy driver (to make sure power save > works). > > Is there a chance that the atomisp driver will return to the kernel? As much as I'd like to say yes, I think this is unfortunately very unlikely. There are a few obstacles to getting a working camera with atomisp: - According to some reports, the driver doesn't work. That's the first thing that would need to be fixed, and without hardware documentation and support from Intel, that would be a difficult (to say the least) task. - Assuming we could fix the driver, we would need to make sure it supports your device. If the atomisp is anything like the IPU3 (a more recent ISP from Intel), there are two different and incompatible sets of ACPI data formats related to the device, one developed for Windows, and one developed for Linux. I expect the atomisp driver to support the latter but not the former. If your device was shipped with Windows, it uses the Windows-specific ACPI data format. Furthermore, it would in that case likely not encode all the information we would need in ACPI, as Windows drivers have the bad habit of hardcoding device-specific data in drivers. At the very least we would need to get the atomisp to support the Windows ACPI data format (which is most likely completely undocumented), and we would need to figure out how to retrieve data that are simply not there. This being said, maybe the atomisp ACPI design was better than the IPU3 and all (or part of) those issues don't exist, but I'd be surprised. - At this point you would (hopefully) have a driver that could capture RAW images. In order to use the camera as a webcam, those images would need to be processed by the ISP that is part of the atomisp. This requires complex image processing algorithm control code in userspace. Intel has not released any open version of such code for the atomisp (or any other platform) to my knowledge, so this would need to be implemented from scratch. The libcamera project could help there, as it provides a framework to host such code, but the atomisp-specific code would still need to be implemented. This is a complex task when the hardware is fully documented, without hardware documentation and thus without knowing how the hardware works, it gets extremely difficult. The task would be orders of magnitude more complex than reverse-engineering a GPU. - Finally, in order for the driver to be merged back in the upstream kernel, it would require massive cleanups, but that's the simplest task of all that is required here. I'm sorry for the bad news, we need to be more vocal blaming hardware vendors for this type of mess. > There are quite a few older tablets and 2in1 devices that would benefit. > Unfortunately I do not understand the removed code (my coding skills are > very basic) and can thus not help to change what ever is necessary to > make it fit for the kernel :-( (does not sound like a beginner project). > However - I would be glad to help out to help testing an ISP driver. > > However - even without the cam it is a very impressing operating system > which I enjoy very much. I would like to thank all of you for your work > that benefits so many people! You're welcome. Your thanks are much appreciated :-) -- Regards, Laurent Pinchart
