SK-AM62: Failed to configure csi-2 DPHY on OVM9284 image sensor configuration with linux sdk

Hi Thorsten,

We've just discovered an issue with the CSI DPHY in the 8.4.1.3 release. This issue was most likely the cause to the capture failure you encountered. There are a few ways to fix the issue.

Get an updated kernel module for the Cadence PHY: 

1. Download the tiny linux wic image from CI/CD snapshot: https://software-dl.ti.com/linux-cicd-report/index.html?section=snapshot&platform=am62xx&snapshot=cicd.2022.10.10.19:06:00.prod -> tisdk-thinlinux-image-am62xx-evm.wic.xz.

2. Flash this wic image to an SD card.

3. Get the Cadence PHY module from the above created SD card: /media/<user name>/root/lib/modules/5.10.140-g0e992913b2/kernel/drivers/phy/cadence/cdns-dphy.ko.

4. Copy the above obtained cdns-dphy.ko to 8.4.1.3 release /lib/modules/5.10.140-g5e63ae91b2/kernel/drivers/phy/cadence/cdns-dphy.ko. You may want to keep a copy of the 8.4.1.3 cdns-phy.ko.

5. Reboot the board.

Alternatively you can just extract the wic.xz image:

mkdir tinyimg && cd tinyimg
7z x ../tisdk-thinlinux-image-am62xx-evm.wic.xz
7z x tisdk-thinlinux-image-am62xx-evm.wic
7z x 1.img
cp lib/modules/5.10.140-g0e992913b2//kernel/drivers/phy/cadence/cdns-dphy.ko <destination>

Get the Cadence PHY driver patch and rebuild the module:

• Git commit having the fix: https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/commit/?h=ti-linux-5.10.y&id=8866ccf9941c4
• Patch download: https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/patch/?id=8866ccf9941c4adb7f740f5995cb06a562086542

Regards,

Jianzhong

Hi Jianzhong,

many thanks for the response. That helped a lot so we don't have this error. 

Two advices I would link to ask you. 

1. The camera OVM9284-RGPA-Z is a monochrome camera, and it support the RAW8/RAW10 format only. What is the MEDIA BUS FMT optin to set in code?
   1. = fmt->code = MEDIA_BUS_FMT_SBGGR10_1X10 and fmt->colorspace = V4L2_COLORSPACE_SRGB?
2. What v4l2-ctl or media-ctl command can be used for capturing an image / photo (RAW format) from the /dev/video0?

Hello Thorsten,

We haven't tested this specific camera. Please refer to the AM62x Linux Academy, the following chapters regarding configuring and using the camera to capture:

• Evaluating camera
• Using camera

Regards,

Jianzhong

Hi Jianzhong, 

the two links help to understand enablement for existing cameras but do not discuss what format changes to be made. 

8/10-bit RAW means any monochrom pixel to output via MIPI interface. 

1. Would this format receive the 10bit RAW format? fmt->code = MEDIA_BUS_FMT_SBGGR10_1X10 and fmt->colorspace = V4L2_COLORSPACE_SRGB

2. What v4l2-ctl or media-ctl command can be used for capturing an image / photo (RAW format) from the /dev/video0?

For the monochrome format, can we add the following codes to support it?

After added above codes, I can see a new format is supported:

But I don’t know if my modification is correct or not, do I need add some more to make it working?

I have tried the above changes with the following command.

• v4l2-ctl -d /dev/video0 --set-fmt-video=width=1280,height=800,pixelformat='Y10 '
• v4l2-ctl -d /dev/video0 --stream-mmap --stream-count=1 --stream-to=test.gray
• for the second the command, cannot exit until I use “Ctrl+C” to exit.

Hi Thorsten,

Let me look at this and get back to you early next week.

Regards,

Jianzhong

Hello Thorsten,

I checked with the SW dev team. In fact, MEDIA_BUS_FMT_Y10_1X10 or MEDIA_BUS_FMT_Y8_1X8 is not yet supported by our driver.

Can you please try MEDIA_BUS_FMT_SGRBG8_1X8 or similar Bayer formats? I've tested MEDIA_BUS_FMT_SGRBG8_1X8 with OV9281 and it works fine.  Since OV9284 and OV9281 have the same output formats, I think MEDIA_BUS_FMT_SGRBG8_1X8 should work for OV9284 as well.

Regards,

Jianzhong

Hello Jianzhong!
I am Li Hang from Continental, I am doing the the driver development for the OV9284 now, I believe this ticket is raised for my question, can you please share the codes of the ov9281 to me as the reference?

Thank you!

Hello Li Hang,

Sorry, but the code wasn't developed by TI and we can't share it with you.

Regards,

Jianzhong