RNG Hardware error

[richardhaydon]

I am using Freescale i.MX6SOLO rev1.2

Attempts to instantiate the RNG in non test mode give job completion with error code

0x2000065b     Hardware error, RNG

What should I check to find the cause please.

CAAM status indicates that entropy is not being generated, ring oscillator not running

[Yuri · Accepted solution]

Hello,

 The RNG Hardware error usually means that the entropy source has
failed to generate entropy, and therefore the RNG cannot instantiate.
  For early engineering samples with CAAM it may be necessary to blow
the RNG trim fuses. This increases the amount of time that CAAM ENG
is given to  generate entropy. Please check it.

From “i.MX_6_Linux_High_Assurance_Boot_(HAB)_User's_Guide.pdf” :

Turn on RNG_TRIM

$ echo 0x00040000 > HW_OCOTP_MEM0
 
  Next, the error  may be caused if the TRNG has been configured with a too
small value for ENT_DLY in RNG TRNG Seed Control Register (RTSDCTL). Please
try to load a value of 1600 for the ENT_DLY.

  Please look at recommendations of section 3.3.2. (RNG Trim fuses)

of app note AN4581 (Secure Boot on i.MX50, i.MX53, and i.MX 6 Series
using HABv4).

http://cache.nxp.com/files/32bit/doc/app_note/AN4581.pdf 

Best regards,
Yuri

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