OMAP-L138: Inquiry about LPDDR Initialization

Hi Experts,

Customer measured AC timing with their system boards. I attached it ( Actual_Measurement_Result.pdf ).

it is really appreciated your quick reply.

Best regards.

Miyazaki

This has been assigned to a hardware expert, however please see that they are not susceptible to 

2.1.5 DDR2/mDDR Controller: mDDR Usage Note in the errata

https://www.ti.com/lit/er/sprz301m/sprz301m.pdf

Hi Mukul,

Thank you for your advice.

I see... Should I ask customer what kind of LPDDR customer are using? I mean, should I clarify LPDDR device name?

Best regards,

Miyazaki

Ensure they are following the initialization steps in the TRM, section 15.2.13.1.  Also ensure they are using https://www.ti.com/lit/pdf/spracq4 to configure the DDR controller and PHY

Regards,

James

Hello James, Mukul,

I shared your comments ith customer. I'd like to wait for your feedback.

Best regards,

Miyazaki

Hi James,

I discussed this issue with customer, and I gathered this issue’s background with calling.

Previously, customer was using LPDDR which is supporting Status Read Register (SRR). However, due to device shortage issue, customer replaced it with other LPDDR device. This LPDDR device does not support SRR, therefore, there is not possibility that this issue is related to  “2.1.5 DDR2/mDDR Controller: mDDR Usage Note” in errata list. First of all, although customer was asking DDR device maker, this maker is asking customer if customer’s system is obeying powerup sequence like JESD209B specification, correctly. Since customer noticed there was violation that is OMAP-L138 does not wait for at least 200usec, they are asking how to control this 200usec.

Customer already read “15.2.13 Auto-Initialization Sequence”, and they understood OMAP’s mDDR initialization sequence is compliant with the JESD209 specification. Certainly, customer is not sure if this issue is related to this 200usec-waiting at this time , however, customer is not able to mention the Memory-vendor that customer is controlling it correctly.

And then, customer tried to understand TI’s spreadsheet, they are not sure if customer is able to control this waiting-time with OMAP-L138’s registers.

Therefore, customer is asking how to control this waiting-period at first. Can we have your expert’s advice/comments on this, please?

If you have any advice what customer should do analysis, would you share your advice, please?

When this issue occurred, it seems device-reset was repeated.

Best regards,

Miyazaki

Hello James-san,

Can I have your further advice for this issue, please?

Best regards,

Miyazaki

Hello James-san,

If customer should do analysis of other points, could you share your further advice, please?

I'll try to request customer to do that.

Best regards,

Miyazaki

Hello James-san,

I’m Miyazaki-san’s customer, Furuya.

As Miyazaki-san reported, we are encountering LPDDR issue after replacing LPDDR with other one now.
We already referred “15.2.13 Auto-Initialization Sequence” in TRM and engineers in Japan and the US each confirmed that ensured our firmware was following the initialization step. 
In addition, we re-checked EMIF spreadsheet and confirmed there were not any miss.
I mean, I have verified that the mDDR configuration in the our bootloader matches the procedure specified in 15.2.13.1 exactly.
But, we are not sure the method how to control this 200usec.
We’d like to request DDR manufacturer to consult this issue, however, we need to fix this JESD209B initialization violation of the before that.

Can we have TI’s advice, as soon as possible, please?

Mass production is stopping now. Your quick reply will be really appreciated.

Best regards,

Furuya