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Target reset when writing OCOTP registers on some devices

Question asked by Bart Thoelen on May 14, 2013
Latest reply on Jun 17, 2013 by Ming On Lai

Hi All,

 

I have a odd situation on our imx28 platform regarding the OCOTP fuses.

 

Some devices will resets after setting HCLK to the original value after programming an OCOTP, i.e. setting the HCLK to 151Mhz again.  The register is written successfully, although.

 

I have tried to change the order in which the VDDIO and the CLK are set back to the original value (after writing the OCOTP registers) in such that now first the VDDIO is set to 3V3 again and then the CLK to 151Mhz - I guessed some logic in the imx could not cope with the higher clockrate on the lower voltage (2V8).  This fixed the issue on most devices but some keep resetting.

 

Strange enough, when configuring the kernel with USB_SUSPEND enabled, all seems to be fixed.  As we use a Gobi3K on our platform and swapping images on that Gobi fails when USB_SUSPEND is set we cannot enable this config.  This is not the big issue here - and maybe is some juice for another discussion.

 

So my question: does anybody have some thoughts on this?  Is the VDDIO power rail used internally in the imx28?  Is there anybody ( wishful thinking )  who has a fix?

 

Thanks,

 

Bart

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