SDP_DISABLE not working?

[m_etairidis]

Hello,

I am trying to set up the i.MX6UL fuses in way that would completely disable the USB serial download and JTAG functionality. My device normally boots from QSPI flash.

I have set the SDP_DISABLE fuse bit as described in the Reference Manual (0x460[17]) as well as the SDP_READ_DISABLE fuse (0x460[18]) and the SJC_DISABLE fuse (0x460[20]). Disabling the JTAG controller seems to work, but the USB serial download feature is still active even though I have set the "disable" fuses.

Reading the fuses via u-boot I get the following:

$ fuse read 0 6

$ Word 0x00000006: 00160000

Any idea what that might be the case?

[Yuri]

Hello,

   Do You use the device of Rev. 1.2 (Maskset ID 2N52P)?

For more details, please refer to Engineering Bulletin EB00854,  mentioned on

i.MX & Vybrid Security Vulnerability Errata - ERR010872, ERR010873 

Have a great day,

Yuri

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[m_etairidis]

Hello Yuri,

thank you for your message. I was aware of ERR010872 and I can't see how it is relevant to my problem. I am actually trying to achieve what ERR010872 is proposing as a workaround, namely to switch off the Serial Downloader completely:

"• For the i.MX 6UltraLite and i.MX 6ULL devices, a customer programmable eFUSE is available to disable the SDP port, thereby completely preventing this vulnerability."

I set what I think is the right fuse (SDP_DISABLE, 0x460[17]) but I am still able to use the Serial Downloader to load an image via USB.

Any idea about why that might be the case?

P.S. my device is 0N52P.

Regards,

Michail G. Etairidis

[Yuri]

Hello,

  Would You please create request \ ticket for further discussion.

Support|NXP 

Regards,

Yuri.