How to distinguish between DDR calibration and power saving feature?

[t-iishii]

Hi

In imx6 Reference manual(IMX6DQRM.pdf), it say that
Power saving features should be disabled before the calibration
process begin.

How to distinguish between DDR3 calibration and power saving feature?

I think, in normal operation, it must enable auto ZQ calibration,
Upon hardware or software self-refresh request assertion,
Disable ZQ calibration first, and enable auto power saving.

Is it correct?

In our customer, when both calibration and automatic power saving are
enable, their LCD output will stop and system will hung-up.

Which mechanism do it happen?

Best regards,
Ishii.

[art]

Q. I think, in normal operation, it must enable auto ZQ calibration, Upon hardware or software self-refresh request assertion, Disable ZQ calibration first, and enable auto power saving. Is it correct?

A. Yes, this is correct.

Q. In our customer, when both calibration and automatic power saving are enable, their LCD output will stop and system will hung-up. Which mechanism do it happen?

A. If the system tries to go to the power saving mode in the middle of the ZQ calibration cycle, it tries to send the self-refresh command to the DDR memory, causing it to hang up.

Have a great day,
Artur

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[linzhang]

#A. If the system tries to go to the power saving mode in the middle of the ZQ calibration cycle, it tries to send the self-refresh command to the DDR memory, causing it to hang up.

How can I trigger it?

[t-iishii]

Artur,

Thank you for your response.

> A. If the system tries to go to the power saving mode in the middle of the ZQ calibration cycle,

> it tries to send the self-refresh command to the DDR memory, causing it to hang up.

I have 2 additional question.

1) you say "middle of the ZQ calibration". that's mean

  * middle of each ZQ calibration cycle.

    ---<ZQ calibration>---<SRE>---<ZQ calibtation>=== Hung up

  * middle of one ZQ calibration operation.

    ---<ZQ calibration>----

                 |-----<SRE>=== Hung up

   which is a correct answer?

 2) In automatic power saving, it will send self-refresh mode if it has no DDR access.

    Is it generate self-refresh command under running ZQ calibration cycle?

Best regards,

Ishii.