Problem with PCI host driver in IMX6 kernel 3.14.28

[jemish_1990]

Hi All,

• We are using IMX6  (IMX6 part number: MCIMX6Q6AVT10AD) based board in our product.
• In our board we have connected Marvell Azurewave module (88W8897) on PCIE bus via M.2 KEY.E connector.
• The issue is that we just enable PCIE related config in our kernel and in kernel log I see that host probe failed with below messages:

imx6q-pcie 1ffc000.pcie: phy link never came up
imx6q-pcie 1ffc000.pcie: DEBUG_R0: 0x00b5bc43, DEBUG_R1: 0x08000000
imx6q-pcie 1ffc000.pcie: Failed to bring link up!
imx6q-pcie 1ffc000.pcie: failed to initialize host
imx6q-pcie: probe of 1ffc000.pcie failed with error -22

• I have go through suggestions provided by NXP community. To disable "CONFIG_PCI_MSI" from kernel config.
• Also removed below two lines from device tree:

        intc: interrupt-controller@00a01000 {
                compatible = "arm,cortex-a9-gic";
                #interrupt-cells = <3>;
-               #address-cells = <1>;
-               #size-cells = <1>;
                interrupt-controller;
                reg = <0x00a01000 0x1000>,
                      <0x00a00100 0x100>;

Still no success.

Are there any suggestions from Hardware or Software perspective? I am attaching my kernel config and device tree for reference. We have taken wandboard as reference. 

Please let me know if anything needed from my side.

Thanks,

Jemish

[jemish_1990]

Hi Igor,

Currently we have decided to migrate to latest kernel of imx6 based on wandboard. And we will use Spark Lan WIFI module which is based on Qualcomm chipset. That's why we will can close this discussion regarding Azurewave module support with PCI host. 

Thanks a lot for your support and help we can close this discussion now.

[igorpadykov]

Hi Jemish

one can try several pcie cards and suggestions on

IMX6Q: Linux boot halts at PCIe config space read 

https://community.nxp.com/thread/383799 

Best regards
igor
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[jemish_1990]

Hi Igor,

Thanks for your response!

We are trying with different suggestions you provided on mentioned link we will update you once we will have something significant.

Thanks,

Jemish

[jemish_1990]

Hi Igor,

• Based on your suggestion we tried different modules and we found there was an issue with Azurewave module we were using.
• We tried with Spark Lan wifi module with which PCI host able to detect module and everything works fine with kernel 4.1.15 of wandboard. Because in kernel 3.14.28 doesn't have support of QCA6174 chipset.
• Then we tried different Azurewave module with which PCI host detect module and it works fine. But is not reliable as Spark Lan. Because with Spark Lan PCI host always detects module (doens't matter we use kernel 3.14.28 or 4.1.15) .But with Azurewave in both kernel we got this issue of random detection on PCI bus. With Azurewave module it got detected sometimes and sometimes not.
• We may move to kernel 4.1.15 or back Spark Lan wifi driver from there.
• Is random detection of Module on PCI host is known issue ? Do you have any suggestion for that? Or is it something we should ask to Marvell ? If it is the issue of WIFI module then we can close this discussion.

Thanks,

Jemish

[igorpadykov]

Hi Jemish

probably module produces less signal power and one can try to tweak

PCIe signal shape with IOMUXC_GPR8 register. May be useful AN4784

PCIe Certification Guide for i.MX 6Dual/6Quad and i.MX 6Solo/6DualLite

https://www.nxp.com/docs/en/application-note/AN4784.pdf 

Best regards
igor