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Altera_Forum
Honored Contributor I
1,171 Views

a problem of PCIe on Cyclone V GT Dev Kit

Hello, 

 

I'm trying to use the PCI Express Avalon-ST DMA reference design (https://www.altera.com.cn/products/reference-designs/all-reference-designs/interface/ref-pciexpress-... (https://www.altera.com/products/reference-designs/all-reference-designs/interface/ref-pciexpress-ava...)),the kit is Cyclone V GT Development kit,but I'm having some troubles with the Linux driver. 

 

I have followed the user manual step by step, but the PC still can't identify the development kit,The PCI express edge connector on development kit is X4 mode,Is it possible to insert a PC's x16 slot?  

 

Im stuck for week right now, reading and looking for the right information...
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5 Replies
Altera_Forum
Honored Contributor I
43 Views

Altera_Forum
Honored Contributor I
43 Views

thanks,I've tried two reference designs,PCIe AVMM with DMA and On-Chip Memory Interface and PCIe AVMM with DMA and DDR3 Memory Interface. 

The development kit is not recognized by the PC,Is it possible to insert a PC's x16 slot?
Altera_Forum
Honored Contributor I
43 Views

I am not sure myself - I know that PCIe x16 is supposed to be backward compatible with x4 (again, I assume there's nothing to change in the BIOS/UEFI). Sorry, I don't work on PCIe related stuff so I don't really have idea on this :(

Altera_Forum
Honored Contributor I
43 Views

Thank you all the same!

Altera_Forum
Honored Contributor I
43 Views

You can in theory insert any PCIe device of any width into any PCIe slot of any width. During enumeration of the PCIe bus the width of each link is negotiated by sensing whether a lane is connected and functional at both ends. 

 

If you plug in a PCIe x4 device into a PCIe x16 slot then during the enumeration process the PCIe switch or RC you've connected it to will detect that there are only four lanes and turn off the unused 12 lanes.
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