PROCESSOR-SDK-AM335X: DDR3 configuration patch

kuanlun chiu

Prodigy 140 points

Part Number: PROCESSOR-SDK-AM335X

Dear sirs,

In below patch, you said "This patch fixes the DDR3 initialization procedure in order to comply with DDR3 standard."

We have encountered DD3 unstable issue and apply this patch indeed fixed it.

I want to ask where should I find the DDR3 standard document that mentioned this initialization procedure.

Would you help to provide some official document to clarify this issue.

Thanks for your help.

over 9 years ago

0 Biser Gatchev-XID over 9 years ago

TI__Guru**** 393215 points

Hi,

The DDR3 standard is a JEDEC document. You can download it from here: www.jedec.org/.../jesd-79-3d

0 kuanlun chiu over 9 years ago in reply to Biser Gatchev-XID

Prodigy 140 points

Hi Biser,

Thanks for your reply.
I have download this document already and read section of initialization sequence.
But I did not find anything related to the modification in u-boot patch.
I hope I could get someone's help to point out which section should I read in this JEDEC document.
Or which document I could find some clue about this issue?

Thanks

0 Biser Gatchev-XID over 9 years ago in reply to kuanlun chiu

TI__Guru**** 393215 points

See the comment in the beginning of the patch:

"This patch fixes the DDR3 initialization procedure in order to comply with DDR3 standard. A 500 us delay is specified between the DDR3 reset and clock enable signal. Until now, this delay was not respected. Some DDR3 chips don't bother but the bigger the RAM becomes the more likely it seems that this delay is needed. We observed that DRAM > 256 MB from
the manufacturer Samsung have an issue when the specification is not respected."

0 Brad Griffis over 9 years ago in reply to Biser Gatchev-XID

TI__Guru*** 125430 points

It is documented in Section 3.3.1 Power-up Initialization Sequence.

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PROCESSOR-SDK-AM335X: DDR3 configuration patch