Re: atomisp kernel driver(s)

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Patrik,

On Wed, Apr 29, 2020 at 07:59:23PM +0200, Patrik Gfeller wrote:
> On 26.04.20 21:17, Laurent Pinchart wrote:
> > On Sun, Apr 26, 2020 at 09:44:30AM +0200, Patrik Gfeller wrote:
> >> Hi Sakari,
> >>
> >> I hope you are well!
> >>
> >> We are currently evaluation (mainly Mauro and Laurent) if it is possible
> >> to continue the work on the atomisp driver. I try to do some tests to
> >> see if the driver works at all using the patches Mauro made. As the
> >> firmware is hardcoded I need specific firmware versions. In an earlier
> >> post related to atomisp you mentioned that you use the following firmware:
> >>
> >> shisp_2400b0_v21.bin
> >> Version string: irci_stable_candrpv_0415_20150423_1753
> >>
> >> I only found the following versions
> >>
> >> shisp_2400b0_v21.bin
> >> Version string: irci_master_20140707_0622
> >>
> >> shisp_2401a0_v21.bin
> >> Version string: irci_master_20140707_0622
> >>
> >> I tried to change the hardcoded string in the code to the version I have
> >> available, but not sure if it loaded the firmware at all. I saw that
> >> there are debug lines to provide more verbose information, but I could
> >> not figure out how to enable those messages:
> >>
> >> atomisp_fops.c
> >>           isp->firmware = atomisp_load_firmware(isp);
> >>           if (!isp->firmware) {
> >>               dev_err(isp->dev, "Failed to load ISP firmware.\n");
> >>               ret = -ENOENT;
> >>               goto error;
> >>           }
> >>           ret = atomisp_css_load_firmware(isp);
> >>           if (ret) {
> >>               dev_err(isp->dev, "Failed to init css.\n");
> >>               goto error;
> >>           }
> >>
> >> If you could provide me the correct firmware file would be highly
> >> appreciated. Maybe you even remember how to enable the more verbose logging?
> > What verbose logging are you talking about ? If you're referring to
> > dev_dbg(), Documentation/admin-guide/dynamic-debug-howto.rst if your
> > kernel is compiled with dynamic debug support, otherwise just
> >
> > #define DEBUG 1
> >
> > at the top of the file.
> 
> Thanks, That was exactly what I was looking for. I've made sure that 
> dynamic debug support was enabled and re-compiled the kernel. Then I've 
> added to the following boot parameter: dyndbg="module atomisp_ov2680 +pm".

Can you try

atomisp_ov2680.dyndbg=+p

? I haven't tested the plain dyndbg argument myself. Make sure it gets
to the kernel with

cat /proc/cmdline

> I do not see debug messages in dmesg or kern.log - but maybe we do not 
> reach those lines yet.

You can add a dev_dbg() at the beginning of the probe function and see
if that one gets printed.

> >> On 25.04.20 04:39, Laurent Pinchart wrote:
> >>> 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