imx28 dcp encryp only once

[jérômedusautois]

Hi,

I try to use DCP to encrypt buffer with OTP key.

I can encrypt buffer only one time for each board reset. After first encrypt, I don't have error but result buffer is always set to initial value.

I try with key in payload and I have same result.

I try for all channel and I have same result.

I try to soft reset DCP and I have same result.

In fact It try many other cases and I have same result : only first DCP command work. All other leave result buffer unchanged.

Can you help me, please.

best regards

Jérôme

[jérômedusautois]

Hi Yuri,

Your first point was the good one!

If I clean cache before starting dcp, all is good.

Thanks,

Have a great day too!

Jérôme

[Yuri · Accepted solution]

Jerome, hello !

1.

Please check if the issue is not concerned with cache coherency.

2.

  Please verify if clear bit operation is used, when accessing  to HW_DCP_STAT(_CLR).

3.

  You may look at FSL Linux BSP.  Please refer to Chapter 20 [Data Co-Processor
(DCP) Driver ] of “MX28_EVK_Linux_Reference_Manual.pdf”. Section 20.6 (Unit Test)
describes Tcrypt as DCP test module.

https://www.freescale.com/webapp/Download?colCode=L2.6.35_1.1.0_ER_SOURCE&appType=license&location=n...

Have a great day,
Yuri

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