topic Re: How to Enable PCIe in imx6Q in i.MX Processors

How to Enable PCIe in imx6Q

zohanlin — Thu, 02 Sep 2021 07:47:27 GMT

Dear guys,

My kernel is v4.9.88 and my board is i.MX6Q.

I refer the link in NXP

https://community.nxp.com/t5/i-MX-Processors-Knowledge-Base/i-MX6Q-PCIe-EP-RC-Validation-System/ta-p/1126624

For enabling PCIe function in imx6Q, I have three questions.

1. Do I need to enable CONFIG_RC_MODE_IN_EP_RC_SYS=y if I want plug a EP mode PCIe device to imx6Q?

2. Are the CONFIG_RC_MODE_IN_EP_RC_SYS & the CONFIG_EP_MODE_IN_EP_RC_SYS only for testing R/W speed between two i.MX boards?

3. Do I need to enable cache for PCIe function in normal case? If yes, how to enable cache for PCIe?

Thanks,

zohan

Re: How to Enable PCIe in imx6Q

igorpadykov — Thu, 02 Sep 2021 09:04:10 GMT

Hi Zohan

1. please use option on that link

"Software configurations
* When building RC image"

2. no

3. suggested to use default dts:

https://source.codeaurora.org/external/imx/linux-imx/tree/arch/arm/boot/dts/imx6q-sabresd.dts?h=imx_4.9.88_2.0.0_ga

Best regards
igor

Re: How to Enable PCIe in imx6Q

zohanlin — Mon, 13 Sep 2021 08:59:20 GMT

Hi igor,

I plugged SIMCOM 5G module(EP mode) to i.MX6Q board,

the PCIe read speed is 1.8 MB/s, write speed is 7.8 MB/s.

I see the i.MX6Q spec it says the i.MX6Q support PCIe 2.0

Why the speed is slower than PCIe Gen 1?

I also done the same test on i.MX6QP EVB without externel OSC.

And the result is almost same as i.MX6Q.

Do you have any suggestion about my problem?

Thanks,

zohan

Re: How to Enable PCIe in imx6Q

igorpadykov — Mon, 13 Sep 2021 23:29:36 GMT

bad performance may be due to noisy signals, one can try steps provided in AN4784 and

check if signal quality is good

AN4784: PCIe Certification Guide for i.MX 6Dual/6Quad and i.MX 6Solo/6DualLite - Application Note

Best regards
igor

Re: How to Enable PCIe in imx6Q

zohanlin — Wed, 15 Sep 2021 08:43:28 GMT

Hi igor,

We don't have those test equipments.

And we have test two 5G modules on i.MX6QP EVB:

(1)SIMCOM SIM8202G-M2

(2)QUECTEL RM502Q-AE

SIMCOM & QUECTEL both have bad upload & download speed.

Their upload speed is about 2MB/s and download speed is about 6MB/s.

Do you have any idea about the issue?