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PCIe EndPoint iMX6SX

Question asked by Paolo Minazzi on Mar 21, 2020
Latest reply on Apr 1, 2020 by Paolo Minazzi


we are trying to connect

  • iMX6SX cpu
  • x86 module

by PCIe.

The iMX6SX must be a PCIe Endpoint.

I need only shared memory between iMX6SX and x86. I do not need interrupt.

Shared memory must be in a region of DDR RAM of iMX6SX.


On iMX6SX I use linux-imx-imx_4.9.88_2.0.0_ga-var01.

On x86 I'm using an EFI shell that allow me to see pci devices and addresses assigned.

I reserve some memory for shared memory, so Linux will not use this.

I boot with mem=128M.


I start using the endpoint configuration used from the validation test.

On Linux I have 


I power-on the iMX6SX and  I see on serial console :

PCIe EP: waiting for link up...


All is OK ... iMX6SX is waiting PCIe link.

Now I reset the x86 module.

As soon as I power-on x86, iMX6SX get the link.

For now all is OK.


Now I have a linux uart console.

On x86 I can see using the EFI shell the PCI configurazione.

I see:

  • my endpoint as Memory controller - RAM memory controller.
  • VID and PID are correct.
  • the address assigned by x86 to BARs.
  • the correct size of the BARs I assigned


The problem is that after some seconds linux freezes.

On the x86 I can see the PCI register of the iMX6SX endpoint.

x86 works OK, does not freeze.

I attach the complete dump of my PCI endpoint.


From the dump I see two strange things:

  1. Command register go to 0.
  2. Received Master Abort:          1


Only for testing, I tried linux-imx-rel_imx_4.1.15_2.1.0_ga and linux-imx-rel_imx_4.14.98_2.0.0_ga.

On 4.1.15 I have seen problem with the PCIe link, with 4.14.98 I have seen something similar what I have seen with 4.9.88.

I did not investigate.


On 4.14.98 I have seen an option in menuconfig.

but I don't think it is the right way to follow.


My final question is if I'm on the correct way using EP config used for Validation Test.

Is this OK as a base for PCIe Endpoint ? If is not complete, what it is missing ?

I realize that I could have setted badly some address in PCI controller, but for now, if none writes (x86 and iMX6SX), I think that this kind of error could not be important.


Thanks for your time,

Best regards,