phy_modify_mmd(9)

📦 version 7.3.1, in nixpkgs unstable

💅 phy_modify_mmd(9) 💅

Okay bestie, so this is a page from the Kernel API Manual and it's literally about phy_modify_mmd — a convenience function for modifying a register on MMD. Yes, that's a lot of M's, no cap, and it's giving "read the register, tweak some bits, write it back" energy and honestly? We're obsessed. 🦋

✨ SYNOPSIS ✨

int phy_modify_mmd (struct phy_device *phydev , int devad , u32 regnum ,
u16 mask , u16 set );

That's the whole signature, character for character, don't come for me. 👑

🎀 ARGUMENTS 🎀

  • phydev — the phy_device struct. Your main character, literally the whole device vibe. 🌸
  • devad — the MMD containing the register you wanna modify. Like, which MMD, babe. Pick one. 🎯
  • regnum — the register number to modify. The exact spot we're messing with. 📍
  • mask — bit mask of bits to clear. This is your "not these ones, thank you" list. ✂️
  • set — the new value of the bits set in mask to write to regnum. So: mask says where, set says what goes there. Iconic duo, honestly. 💖

⚠️ NOTE ⚠️

MUST NOT be called from interrupt context, because the bus read/write functions may wait for an interrupt to conclude the operation.

And this one is not a vibe-optional thing, bestie — this is a hard MUST NOT. 😭 Like, do not do it. If you're in interrupt context and you call this, the bus read/write functions might just sit there waiting for an interrupt to conclude the operation, and next thing you know it's giving deadlock, not slay. 💀 Keep this one out of interrupt context, fr fr.

🔗 SEE ALSO 🔗

Kernel file ./drivers/net/phy/phy-core.c — and the whole friend group, in this exact order so pls don't @ me:

That's the full squad, all 27 of them, every single one accounted for. 🫶 No one gets left behind on my watch. 🌈

So yeah, that's phy_modify_mmd(9) — mask the bits, set the bits, don't do it in interrupt context, and you're golden. 🧚

Big kiss from ./drivers/net/phy, dated October 2026 — that's the source/version and the date, all wrapped up in a cute little sign-off, mwah. 💜✨🎀

📦 where this page comes from