topic How to force LS1012A PCIe into Gen 1 mode? in Layerscape

How to force LS1012A PCIe into Gen 1 mode?

jasonwu0527 — Tue, 31 Jul 2018 08:08:57 GMT

I installed the PI7C9X2G304SLBFDE PCI-E switch kit on LS1012ARDB, but sometimes it can't be detected PCI-E switch.

I would like to force it into Gen 1 mode for testing, how to modify the drivers and force Gen 1 mode?

Thank you.

Can detect:
root@TinyDistro:~# cat /proc/bus/pci/devices
0000 19578100 1e 0 0 0 0 0 0 4040000000 0 0 0 0 0 0 800 pcieport
0100 12d82404 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 pcieport
0208 12d82404 1f 0 0 0 0 0 0 0 0 0 0 0 0 0 0 pcieport
0210 12d82404 20 0 0 0 0 0 0 0 0 0 0 0 0 0 0 pcieport
0218 12d82404 21 0 0 0 0 0 0 0 0 0 0 0 0 0 0 pcieport

Not detect:
root@TinyDistro:~# cat /proc/bus/pci/devices
0000 19578100 1e 0 0 0 0 0 0 4040000000 0 0 0 0 0 0 800 pcieport

Re: How to force LS1012A PCIe into Gen 1 mode?

yipingwang — Wed, 08 Aug 2018 08:54:36 GMT

Hello Jason Wu,

You could change Link_Control_2_Register[T_LS] register value to force link speed down to Gen1.

The offset of this register is 0xA0, PEX1 address is 0x3400000.

Under u-boot

=> md 0x34000a0 1
034000a0: 00010002 ....
=> mw 0x34000a0 0x00010001

=> md 0x34000a0 1

034000a0: 00010001

Have a great day,
TIC

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