Questions about expansion rom of i.mx 6solox pcie ep

[jinhua]

Hi ,

   We use i.mx 6solox as a pcie ep connected to a x86 board. On the x86 board, we can find 64k memory space used for 

expansion rom in the pcie configuration space, offset 0x30. Here are my questions:

   Q1: Is it useful or useless about the expansion rom space?

   Q2: Is there any way to disable the rom space ? Not only clear the enable bit, but return all 0s after writing 0xFFFFFFFE to the PCIE_EP_EROMBAR field(Now a value of 0xFFFF0000 returns, that stands for 64KB).

   Thanks very much!

[jinhua]

Hello everyone,

   I dont think this is a single case on x86 platform.. Anyone develops imx6solo as a pcie ep to x86 platform, the imx6 system may hang while x86 power on? I found the rom space may cause this issue..

[jinhua]

Hi,

    I found another issue, as I said, i.mx6 is a pcie ep connected to a x86 board. On the x86 side, while writing a 0xFFFFFFFF to the i.mx6 pcie configuration space 0x30, sometimes PCIE_EP_EROMBAR and PCIE_EP_EROMMASK could be both overwrited, sometimes both not. Why did this happen?

[jinhua]

I've found the way to disable expansion rom, thanks!

[BiyongSUN · Accepted solution]

expansion rom  is a implementation. Need your engineer who's working on i.MX6 to implement it.

If you have experience on some devices you connect to, which has   expansion rom. Because the devices are implemented the expansion rom. Not just get a board with suppor the ep already has the expansion rom. For expansion rom is kind of application base on the pcie protocol.

[igorpadykov]

Hi Jin

seems it is not used in pcie examples

i.MX6Q PCIe EP/RC Validation System 

probably it may be useful, however this may depend on use case

Best regards
igor
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