About DDR3 DQS Gating, Write and Read Delay Code Example in i.MX6DQ.

keitanagashima — Mon, 16 Nov 2015 10:26:39 GMT

Dear All,

Hello.

Refer to "19 DDR Calibration Code Examples" in AN4467 i.MX 6 Series DDR Calibration, Rev. 2.

===========

Code examples in this section are for 64 bit of DDR data (1 channel 64-bits DDR3, 2 channels 32-bits LPDDR2).

===========

My customer is using 1 channel 64-bits DDR3 with i.MX6DQ.

Next, refer to the below code in "19.2 DDR3 DQS Gating, Write and Read Delay Code Example".

===========

// Issue a write access to the external DDR device by setting the bit SW_DUMMY_WR (bit 0)

// in the MPSWDAR0 and then poll this bit until it clears to indicate completion of the write access.

reg32setbit((MMDC_P0_IPS_BASE_ADDR + MPSWDAR_OFFSET), 0);

while(reg32_read((MMDC_P0_IPS_BASE_ADDR + MPSWDAR_OFFSET)) & 0x00000001);

===========

Finally, refer to "44.12.68 MMDC PHY SW Dummy Access Register (MMDCx_MPSWDAR0)" in IMX6DQRM(Rev.3).

===========

For Channel 0: All

For Channel 1: DDR3_x64, LP2_2ch_x16, LP2_2ch_x32

===========

[Question]

[Q1]

In case of DDR3 64 bit access, is it necessary to set "SW_DUMMY_WR" for both of Channel 0 and 1?

(I think that it doesn't need. User should set it only for Channel 0.)

[Q2]

I have understood as the following about MMDCx_MPSWDAR register.

- MMDCx_MPSWDAR[1:0] for channel 0

- MMDCx_MPSWDAR[5:2] for channel 0 & 1 : DDR3_x64

Is my understanding right?

Best Regards,

Keita

Re: About DDR3 DQS Gating, Write and Read Delay Code Example in i.MX6DQ.

Yuri — Wed, 18 Nov 2015 05:32:39 GMT

Keita, hi !

You are right, an user should set SW_DUMMY_WR only for Channel 0.

Control bits of MMDCx_MPSWDAR ([1:0]) affect channel 0 (64-bit) [x=0].

Data compare results bits of MMDCx_MPSWDAR ([5:2]) relate to corresponding

byte lanes [x=0,1].

Have a great day,

Yuri

-----------------------------------------------------------------------------------------------------------------------

Note: If this post answers your question, please click the Correct Answer button. Thank you!

-----------------------------------------------------------------------------------------------------------------------