On board Implemented with i.MX7 Dual, there is an issue where approximately 0.7% of certain wireless LAN modules connected to PCIe cannot be link up.
PCIe compliance test is conducted on boards Implemented with i.MX7 Dual, and no problems were found with respect to signal quality.
There are also wireless LAN modules that work well with this board.
For PCs Implemented with Intel and other SoCs, link up. Therefore, the wireless LAN module is not malfunctioning.
The following error message is output.
imx6q-pcie 33800000.pcie: phy link never came up
imx6q-pcie 33800000.pcie: Link never came up
imx6q-pcie 33800000.pcie: failed to initialize host
imx6q-pcie: probe of 33800000.pcie failed with error -110
I decoded the error code, it seems that the LTSSM current state is stuck at 0x2 (S_POLL_ACTIVE).
# ./imx6-pcie-decoder
LTSSM current state: 0x2 (S_POLL_ACTIVE)
PIPE transmit K indication: 0
PIPE Transmit data: 0x4a
Receiver is receiving logical idle: no
Second symbol is also idle (16-bit PHY interface only): no
Currently receiving k237 (PAD) in place of link number: no
Currently receiving k237 (PAD) in place of lane number: no
Link control bits advertised by link partner: 0x0
Receiver detected lane reversal: no
TS2 training sequence received: no
TS1 training sequence received: no
Receiver reports skip reception: no
LTSSM reports PHY link up: no
A skip ordered set has been transmitted: no
Link number advertised/confirmed by link partner: 0
Application request to initiate training reset: no
PIPE transmit compliance request: no
PIPE transmit electrical idle request: no
PIPE receiver detect/loopback request: no
LTSSM-negotiated link reset: yes
LTSSM testing for polarity reversal: no
LTSSM performing link training: no
LTSSM in DISABLE state; link inoperable: no
Scrambling disabled for the link: no
When I checked the signal with an oscilloscope, it appeared that the amplitude of the signal input to i.MX7 Dual's PCIE_RX_P and PCIE_RX_N was a little small.I tried changing the register below, but it didn't work.
PCIE_PHY_TRSV_REG21 4:0 EMP_LVL[4:0]
PCIE_PHY_TRSV_REG22 5:0 DRV_LVL[5:0]
PCIE_PHY_TRSV_REG26 6:4 SQTH[2:0]
PCIE_PHY_TRSV_REG36 3 TX_SWING
I've seen multiple similar issues in the forums, but I haven't been able to resolve them.
Please let me know if you have any information to resolve the issue.
Regards,
mio.
