topic Re: Can I read/write TLP packet including 512 Bytes payload via PCIe in i.MX6? in i.MX Processors

Can I read/write TLP packet including 512 Bytes payload via PCIe in i.MX6?

massohy — Wed, 22 Aug 2018 04:23:14 GMT

Dear All,

I want to read/write large TLP packet.

I read this post.

https://community.nxp.com/message/350342

It have been concluded that max payload is 128 byte.

I understood CX_MAX_MTU, CC_SLV_MTU and CC_MSTR_BURST_LEN are fixed.

If I change Max_Payload_Size and Max_Read_Request_Size in PCIE_RC_DConR, then can I process TLP packet including 512 byte payload with PCIe in i.MX6?

Best Regards,

Re: Can I read/write TLP packet including 512 Bytes payload via PCIe in i.MX6?

jamesbone — Thu, 23 Aug 2018 17:18:56 GMT

Regarding to the PCIe RC driver contained in NXP Linux BSP, there is one outbound region used to access the CFG space of PCIe EP.The outbound TLP would be issued, when the

PCIe EP CFG IO APIs(imx_pcie_rd_conf/imx_pcie_wr_conf) are called by PCIe EP driver.

The following is the snapshot of the PCIe protocol analyzer.

One outbound TLP when the CFG space of PCIe EP is accessed.

Re: Can I read/write TLP packet including 512 Bytes payload via PCIe in i.MX6?

massohy — Tue, 28 Aug 2018 09:51:48 GMT

Dear jamesbone,

Thank you for your reply.

I cannot decide that my understanding is correct or not, you say, driver of PCIe RC have only one region and it is for CFG space of PCIe EP, it cannot keep CFG data of PCIe RC in i.MX6. CFG space of PCIe RC in i.MX6 can be accessed only from PCIe EP, ARM CPU in i.MX6 is cannot change it.

That is that I cannot change Max_Payload_Size and Max_Read_Request_Size, and I cannot change max payload size of TLP packet of PCIe in i.MX6 from 128bytes.

Do I mistake them?

Best Regards,