Application Note to CAN/402 Boards
bcdedit /set {current} pciexpress forcedisable
4. Restart your computer.
NOTICE
If you disable the PCI Express Native mode this may cause loss of other system
features, such as Hot Plug, which requires the PCI Express Native mode (see link to
MSDN for more details).
To restore the previous state type the following commands:
bcdedit /deletevalue {current} pciexpress
or
bcdedit /set {current} pciexpress default
Links to further Information:
• About
BCDEdit /set
command:
https://msdn.microsoft.com/en-us/library/windows/hardware/ff542202%28v=vs.85%29.aspx?ppud=4
• About PCI Express Native Control:
https://msdn.microsoft.com/en-us/library/windows/hardware/dn631753%28v=vs.85%29.aspx
• ACPI website:
• PCI-SIG website:
10.2 Linux Operating System
Potential Interoperability Problem caused by Active State Power Management
Reconfiguration
Problem Description
Recent Linux kernels try to reconfigure and optimize the Active State Power Management settings
of PCI Express links. In the course of the reconfiguration the kernel triggers an erratum of the PCI-
to-PCIe reverse bridge PI7C9X111SL that is used on the shown products. Caused by this erratum
the PCIe link stays in the link retraining state and is not usable.
This can be diagnosed by looking at the lspci output for the PCIe device behind the Pericom bridge
that looks like this in the failure case:
root@host# lspci -s 3:0.0 -v -x
03:00.0 CANBUS: ESD Electronic System Design GmbH Device 0402 (rev ff) (prog-if ff)
!!! Unknown header type 7f
00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
10: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
20: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
30: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
Page 38 of 43
Hardware Manual • Doc. No.: C.2049.21 / Rev. 1.5
CAN-PCI/402
