HS_CURR_LEVEL Offset Adjustment Procedure issue


I try to change HS_CURR_LEVEL value via devmem2 utility.
But I can’t change any bit in FUSE_USB_CALIB register:

demo@tegra-ubuntu:~$ sudo devmem2 0x038201F0 w 0xAAA8891
/dev/mem opened.
Memory mapped at address 0x7f9a1a6000.
Value at address 0x38201F0 (0x7f9a1a61f0): 0xAAA8892
Written 0xAAA8891; readback 0xAAA8892

Written value is not equal to readback value.

What do I do wrong?

Is it specific to writing 0x038201F0? Please try other registers and check if the issue is specific to the register.

Technical reference manual for Xavier NX is missing on Nvidia download center.
Could you provide it, or what register do I have to try without damage?

Please check technical reference manual for Xavier. It is same for Xavier and Xavier NX.
Tuning and Compliance Guide is different for Xavier and Xavier NX.

I am trying to find this register in TRM and have a problem.

According to the Jetson_Xavier_NX_Tuning_and_Compliance_Guide_Application_Note_DA-09890-001_v1.2.pdf
HS_CURR_LEVEL values for ports 0, 1 and 2 are located in one register, named FUSE_USB_CALIB with address 0x038201F0:

But in TRM, there is no any FUSE_USB_CALIB with address 0x038201F0.

Moreover, FUSE_USB_CALIB values are located in three separates registers, named

Could you please clarify this issue.


Could you also try to use busybox devmem to write that register (0x038201F0)?


I don’t know how to use busybox devmem. Could you explain it?

And why there is difference between register’s description?

Table 5 in Tuning and Compliance Guide is correct. It should work fine without issue. Do you enable USB2-0 in device tree? Another possibility is the port is not enabled so the value is not changed.


USB is enabled.
Register 0x038201F0 is not accessible for writing:

demo@tegra-ubuntu:~$ sudo devmem2 0x038201F0 w 0xAAA8891
/dev/mem opened.
Memory mapped at address 0x7fa3e58000.
Value at address 0x38201F0 (0x7fa3e581f0): 0xAAA8892
Written 0xAAA8891; readback 0xAAA8892

Further, I decided to try write register XUSB_PADCTL_USB2_OTG_PAD0_CTL_0_0
Bits 5:0 are HS_CURR_LEVEL (for port 0).

Register XUSB_PADCTL_USB2_OTG_PAD0_CTL_0_0 has address 0x03520088

demo@tegra-ubuntu:~$ sudo devmem2 0x03520088 w 0x2CC88D1
/dev/mem opened.
Memory mapped at address 0x7fb4ac4000.
Value at address 0x3520088 (0x7fb4ac4088): 0x2CC88D2
Written 0x2CC88D1; readback 0x2CC88D1

And this register writes OK.

So, Table 5 in Tuning and Compliance Guide does NOT work.

Why register 0x038201F0 in Table 5 is not writable and its description is missing in TRM?


Does your “register write ok” mean your HS_CURR_LEVEL is also adjusted? or you just mean you can write register succesfully?

“register write ok” means that HS_CURR_LEVEL value also changes. It related to XUSB_PADCTL_USB2_OTG_PAD0_CTL_0_0 register.

Through 0x038201F0 register (which absent in official TRM) I can read HS_CURR_LEVEL value, which I wrote via XUSB_PADCTL_USB2_OTG_PAD0_CTL_0_0 regisre.
But I can’t write 0x038201F0.

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Let me check with the owner of this document for this situation. Thanks.

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Just clarify this with teams. The conclusion for the whole procedure is

  1. read the value from fuse register (0x038201F0) → got current value.
  2. Tune the value in XUSB_PADCTL_USB2_OTG_PADx_CTL_0_0 register until it meets the expectations.

The 0x038201F0 is just a fuse register which cannot be written. Only can be adjust by using XUSB_PADCTL_USB2_OTG_PADx_CTL_0_0 mentioned on the tuning guide.

Thank you for clarification.

But what is the sense of fuse register (0x038201F0), if I can read values from register XUSB_PADCTL_USB2_OTG_PADx_CTL_0_0 directly?

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