PCIE slows down after running the DSP program one time

Kim Steiner

Hi. I am using the DM8148, pcie configured as RC mode, with C6657, pcie configured as EP mode. The first time the ARM and DSP are loaded and run the time for pcie read is faster (9ms). If I stop the application and reload and run, the pcie read is slower (18ms). In order to get back to the faster pcie read, I have to cycle power on the device and reload and run again, otherwise the pcie read time takes 18ms always. What could be slowing PCIE read down? Any suggestions on where to look? PCIE write seems to always be the same speed.

Thanks,

Kim

over 9 years ago

0 Pavel Botev over 9 years ago

TI__Guru**** 170625 points

Hi Kim,

Are you using DM8148 TI EVM or custom board?

Are you using EZSDK/PSP?

BR
Pavel

0 Kim Steiner over 9 years ago in reply to Pavel Botev

Intellectual 770 points

Hi Pavel,

We are using a custom board. We use ezsdk version 5_05_02_00 and linux PSP 04.04.00.02.

Thanks,

Kim

0 Pavel Botev over 9 years ago in reply to Kim Steiner

TI__Guru**** 170625 points

Kim,

Can you try with the latest linux kernel available at the below location:
http://arago-project.org/git/projects/?p=linux-omap3.git;a=shortlog;h=refs/heads/ti81xx-master

Try also to reproduce this issue on the DM814x TI EVM.

See also the performance wiki:
processors.wiki.ti.com/.../TI81XX_PSP_04.04.00.02_Feature_Performance_Guide

BR
Pavel

0 Kim Steiner over 9 years ago in reply to Pavel Botev

Intellectual 770 points

Hi Pavel,

I will try these things. By the way, just to be clear, the C66x is reading the data from the DM8148 and so the C66x initiates the PCIE read. This is what we are timing. And on the C66X, the PCIE reads/writes use EDMA. Does this make a difference? Also, because this seems to be an issue on the C66x, did I post to the correct forum?

Thanks,
Kim

0 Pavel Botev over 9 years ago in reply to Kim Steiner

TI__Guru**** 170625 points

Kim Steiner said:
Also, because this seems to be an issue on the C66x, did I post to the correct forum?

This is DM814x forum. For C66x issues, check in its forum.

BR
Pavel

0 Kim Steiner over 9 years ago in reply to Pavel Botev

Intellectual 770 points

Ok I moved this to the Keystone C66 forum. Thanks.

0 tamo2 over 9 years ago in reply to Kim Steiner

Expert 1670 points

Hi Pavel,

Would it be possible that somehow only READ gets GEN 1 speed while WRITE is still at GEN2 speed? I don't think that is possible but I wanted to double check with you anyway.

Thanks,
tamo2

0 Pavel Botev over 9 years ago in reply to tamo2

TI__Guru**** 170625 points

tamo2 said:
Would it be possible that somehow only READ gets GEN 1 speed while WRITE is still at GEN2 speed?

I can not find such option in DM814x PCIe TRM. See also if the below wiki will help:

BR
Pavel

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PCIE slows down after running the DSP program one time