16bit mode with embedded data line and optical blank read as main frame data

[will127534]

Hi there,

I'm working on IMX585 driver for upstreaming and thus start to look at the ClearHDR 16bit mode more closely.
I noticed that with 16bit mode and capture data with rpicam-raw, I'm seeing additional line and optical blank in the RPI5 captured data while RPI4/CM4 did not.

Here is the capture with RPI5, zoomed in to the top left corner

Here is the same driver captured from CM4, zoomed in to the top left corner

Not quite sure what info/debug log needed to do further debug so let me know if you need more info.

Thanks,
WillWhang

[naushir]

So If I understand correctly, the issue is the dark banding on the top of the image right?

It might be we are seeing shielded pixels? Does the datasheet specify what packet ID these are transmitted with?

[will127534]

The first row is actually embedded data, and the dark rows are optical blank.
Same mode on VC4 I didn't see those shows up in the raw data.

0x37 for Optical Blank, 0x12 for embedded data, 0x2E for framedata.
Should be the standard CSI-2 16bit frame format.

[naushir]

This is possibly related to the discussion on #99 about reverting raspberrypi/linux@98b1f0d. Is this commit reverted in your tree?

[will127534]

Yes it is

[naushir]

I can see how the embedded data gets into the buffer stream - do you have embedded data enabled in the libcamera/cam_helper layers? If not, can you enable it and that should route the first line into an embedded data buffer (which you can just ignore). For the optical pixels, that needs a bit more thinking.

[naushir]

Ok, with the change in raspberrypi/linux#6926, you ought to be able to get the image data in the main buffer, and if enabled, embedded data + optical shielded pixels in the second buffer. You should not have to revert raspberrypi/linux@98b1f0d either.

Note that as before, the statistics for the 16-bit format will not be usable.

[will127534]

Hi Naushir,
without reversing that commit, even though there is no more additional data in the frame but the raw capture doesn't seems to be correct, here is the same zoom-in section of the top left corner:

embedded data is enabled in both driver and libcamera cam_helper.

[will127534]

Oh wait I just realized that is a update 7 hours ago, will try it later

[will127534]

Okkk with the latest 6.12.y, I'm still seeing the same thing

[naushir]

raspberrypi/linux#6926 has not been merged yet. Presumably you built the kernel manually or got the change via rpi-update?

[will127534]

Ah I see, yes I build/pull the kernel from the latest 6.12.y branch but not the change, I thought it is the latest one because I see you force-push something.

[naushir]

You can get the kernel from CI with

sudo rpi-update pulls/6926

[will127534]

Thanks! Got the patch up and running, but I don't think it is working.
Here is the patch:

Here is the preview from rpicam:

Here is the raw file

Guess I really need to have a test pattern to see what's going on, but I don't have the datasheet info on that at the moment.

[naushir]

I assume your libcamera library is up-to-date, as there will be an endian swap that needs to be applied raw buffer in the pipeline handler code.