JetPack 5.1 + GMSL cameras: Deskewing

[thomas.hamboeck]

Hi,

we are currently porting our system from L4T 32.7.2 to 35.1.0 and experienced some issues with the GMSL cameras we use. After a lot of debugging we pinpointed the problem now to the newly introduced deskewing mechanism if the data rate is >1.5Gbps.

To understand the situation a bit better:
Who waits for the deskewing? The RT-CPU?
In case we want to implement deskewing correct we are required to get our camera firmware patched that it supports it, right?
Would there be a way to deactivate the wait-for-deskewing for legacy cameras (where we aren’t able to change the firmware)? (thinking of patching the kernel module or the RCE/SCE firmware)

Also i checked for the device tree flags for deskewing, but it appears that they aren’t read anywhere (and serve only documentation purposes?)

kernel/nvidia/drivers/media/platform/tegra/camera/sensor_common.c:					"deskew_initial_enable", &temp_str);
kernel/nvidia/drivers/media/platform/tegra/camera/sensor_common.c:		signal->deskew_initial_enable =
kernel/nvidia/drivers/media/platform/tegra/camera/sensor_common.c:		signal->deskew_initial_enable = 0;
kernel/nvidia/drivers/media/platform/tegra/camera/csi/csi.c:	deskew_enable = sig_props->deskew_initial_enable;
kernel/nvidia/include/media/tegra-v4l2-camera.h:	__u32 deskew_initial_enable;

Best Regards
Thomas

[andres.artavia]

Hi @thomas.hamboeck ,
Not sure if there is a way to disable it without a custom firmware, but depending on the camera it can be just a register that controls if the deskew signal is sent, if you have access to the driver and the datasheet of the sensor you may be able to implement the change. You can check more over here

Regards,
Andres
Embedded SW Engineer at RidgeRun
Contact us: support@ridgerun.com
Developers wiki: https://developer.ridgerun.c om/
Website: www.ridgerun.com

[thomas.hamboeck]

Hi Andres,

thanks for that suggestion! The problem is that right before the camera sensor (Imager + ISP) there is a chip (MCU) translating/shadowing the real camera registers, where we sadly don’t have access to the firmware, limiting us settings registers on the sensor itself.

Best Regards
Thomas