meta-ampere: ampere-usbnet: Ignore link carrier state

The virtual LAN over USB (usb0) connection between BMC and HOST is
locally utilized by the Redfish Host Interface. It is configured with
a static IPv4 address '192.168.0.10' by the network configuration
file [1] '00-bmc-usb0.network'.

Returning to the Ampere Altra Mt. Jade platform, an AC power cycle
caused the usb0 IP address to be lost [2]. The `ipmi lan print 3`
command gives a zero IP address on which HOST has not yet initiated
the PCIe USB device, which was caused by the usb0 link not being
ready. The solution was determined and well-tested. However, the same
issue with the upstream driver in edk2 is still present today.
Therefore, a clean solution ought to be used to fix it.

This patch sets ConfigureWithoutCarrier to 'yes' to allows usb0
interface to retain the static IP address even if the physical
carrier link is down. This helps HOST UEFI firmware to retrieve the
IP address information using the `IPMI lan print 3` command to
populate the SMBIOS Type 42 for the subsequent redfish discovery even
when the usb0 link is not yet established.

Tested with the following steps:
1. Check the usb0 IP address by the command `ip a`. The IP
   192.168.0.10 should be shown in the command output.
2. Check the `ipmi lan print 3`. Since the IP address is available,
   the IP address shown in the command output should be idential with
   the one in step 1.
3. `networkctl down usb0` - Set the usb0 link down.
4. Run again step 1 & 2. The usb0 IP address should be retained.
   Without this patch, it returns all zeros.

[1] https://www.freedesktop.org/software/systemd/man/latest/systemd.network.html
[2] https://den-bugzilla.amperecomputing.com/show_bug.cgi?id=92830

Signed-off-by: Nhi Pham <nhi@os.amperecomputing.com>
Change-Id: I1b1375082ea70510c1ea708947d7f796f6ba7624

0 files changed, 0 insertions, 0 deletions