mdiobus_read_nested(9)

📦 version 7.3.1, in nixpkgs unstable

💖 mdiobus_read_nested(9) 💖

okay bestie, so this is mdiobus_read_nested from the Kernel API Manual — it's the nested-flavoured twin of mdiobus_read, and yes it's exactly as niche and exactly as iconic as it sounds 🎀

✨ NAME ✨

mdiobus_read_nested — literally the Nested version of the mdiobus_read function, no cap 💅

🌸 SYNOPSIS 🌸

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

🦋 ARGUMENTS 🦋

  • bus — the mii_bus struct 🚌
  • addr — the phy address 📍
  • regnum — register number to read 📖

⭐ RETURN ⭐

It gives you the register value if it worked, and a negative error code if it didn't 😭 — that's the whole vibe check.

💜 DESCRIPTION 💜

So like, in case of nested MDIO bus access, you avoid lockdep false positives by using mutex_lock_nested. that's it, that's the tea 🍵 the way this function exists purely to keep lockdep from panicking over nothing?? obsessed 🫶

👑 NOTE 👑

🚨 MUST NOT be called from interrupt context, because the bus read/write functions may wait for an interrupt to conclude the operation. like fr fr, do NOT do it, it will not slay 💀

🌈 SEE ALSO 🌈

Kernel file ./drivers/net/phy/mdio_bus.c — and the whole friend group:

and that's the whole page, bestie!! sourced straight from ./drivers/net/phy, dated October 2026 — mwah, go read some registers responsibly 💋✨💖

📦 where this page comes from