How many kbps does TX2 isomgr support

Hi everyone,

I use TX2 the bsp version is R32.3.1.I debug camera driver, the kernerl output error log as below:

misc tegra_camera_ctrl: tegra_camera_update_isobw: failed to reserve 7500000 KBps with isomgr

How many kbps does the TX2 isomgr support? Thanks.

Adjust the pix_clk_hz and below property depend on your sensor.

num_csi_lanes = <2>;
 		max_lane_speed = <1500000>;
 		min_bits_per_pixel = <10>;
 		vi_peak_byte_per_pixel = <2>;
 		vi_bw_margin_pct = <25>;
 		max_pixel_rate = <160000>;
 		isp_peak_byte_per_pixel = <5>;
 		isp_bw_margin_pct = <25>;

Hi haneCCC,

I use three sensors and and any of them output speed is 2.5Gbps/lane. I config tegra-camera-platform node as blow:

num_csi_lanes = <12>;
max_lane_speed = <2500000>;
min_bits_per_pixel = <10>;
vi_peak_byte_per_pixel = <2>;
vi_bw_margin_pct = <25>;
isp_peak_byte_per_pixel = <5>;
isp_bw_margin_pct = <25>;

Use this config the max isobw is 7500000 KBps. Does Tx2 support this config? Thanks.

TX2’s board design can only support to 1.5G per lane.

The TX2 TRM describes: NVCSI (v1.0 – Parker) Peak bandwidth in D-PHY option (Gbps) is 30 (2.5x 4 X3). In other words TX2 support 2.5Gbps per lane.Why do you say it only support to 1.5Gbps per lane?

Yes, the chip was support to 2.5G however the carrier board design not support to 2.5G though.

We do not use nvidia carrier board we design our carrier board. Does TX2 module support 2.5Gbps?

Yes.

Hi Trumany,

My question is that the kernel output log misc tegra_camera_ctrl: tegra_camera_update_isobw: failed to reserve 7500000 KBps with isomgr

How many kbps does the TX2 isomgr support? Thanks.

@kenny
Have a check below code. You print it out to know the max

…/kernel/nvidia/drivers/video/tegra/camera/tegra_camera_platform.c

vi_iso_bw = ((num_csi_lanes * max_lane_speed) / bits_per_pixel)
  				* vi_bpp * (100 + vi_margin_pct) / 100;
  	isp_iso_bw = max_pixel_rate * isp_bpp * (100 + isp_margin_pct) / 100;
  	if (vi_iso_bw > isp_iso_bw)
  		info->max_bw = vi_iso_bw;
  	else
  		info->max_bw = isp_iso_bw;

Hi ShaneCCC

I have printed the info->max_bw the value is 7500000, but when the capture 3 camera video, the kernel output error log as blow

misc tegra_camera_ctrl: tegra_camera_update_isobw: failed to reserve 7500000 KBps with isomgr

I think the 7500000 is too large. I want to know how many ‘info->max_bw’ could be set the kernel not output the error log.Thank.

Could you please check the __tegra_isomgr_reserve() in below file to check why it failed to reserve the bandwidth?

kernel/nvidia/drivers/platform/tegra/mc/isomgr.c