The existing init() resets the chip, sets up descriptor rings, and
enables TX+RX. It does not read phys_sts, so a driver that comes
up on bare metal with the link not yet up (autoneg in progress,
no cable, or forced-power-down from the BIOS) silently
transmits into a dead medium.
Add a single phys_sts read at the end of init(). The Realtek
part numbers bits as: bit 0 = link up, bit 1 = 100 Mb/s,
bit 2 = 1000 Mb/s, bits 4-5 = duplex encoding. When the link
is not up, log a warn!() with the raw phys_sts byte so the
operator can correlate with the link partner. When the link
is up, log the detected speed as info!().
This is a real surface artefact (visible in the dmesg/log)
and does NOT introduce any new registers or commands; the
chip reports phys_sts on every read regardless of whether
the driver queries it.
The full PHY access (MII writes to PHY register 0x1F to read
the chip version, then BMCR soft-reset + autoneg advertisement)
remains [DEFERRED] until we have an MDIO read/write
infrastructure exposed in redox-driver-sys or linux-kpi
that works with the Redox MII bus scheme.
Red Bear OS
cca052338d