mdiobus_c45_read(9)

📦 version 7.3.1, in nixpkgs unstable

🌸 mdiobus_c45_read — NAME 🌸

Sooo bestie, this is mdiobus_c45_read — the convenience function for reading a given MII mgmt register. That's it, that's the whole vibe: it reads a register for you so you don't have to do the grubby low-level dance yourself 🎀

(btw you're in the Kernel API Manual, section 9 — welcome, make yourself comfy 💅)

✨ SYNOPSIS ✨

int mdiobus_c45_read (struct mii_bus *bus , int addr , int devad , u32
regnum );

🫶 ARGUMENTS 🫶

  • bus — the mii_bus struct. The whole bus situation, the main character of this call.
  • addr — the phy address. Which phy we're talking to, no cap.
  • devad — device address to read.
  • regnum — register number to read.

💖 RETURN 💖

The register value if it all goes well — yay ✨ — and a negative error code on failure 😭 (so like, check it, fr fr).

💀 NOTE 💀

MUST NOT be called from interrupt context. Not a suggestion, a MUST NOT, okay?? The reason is because the bus read/write functions may wait for an interrupt to conclude the operation — so if you're already in an interrupt, you'd be waiting on yourself and that's giving deadlock energy 🙈💀

🦋 SEE ALSO 🦋

Kernel file ./drivers/net/phy/mdio_bus.c plus this whole little family of friends:

okay that's the whole page, you ate it 💅✨

— source ./drivers/net/phy, October 2026, straight outta the Kernel API Manual. mwah, go read some registers responsibly 🌈👑🍓

📦 where this page comes from