phylink_cap...speed_duplex(9)

💅 phylink_cap_from_speed_duplex (9) — Kernel API Manual, bestie edition 🎀

okay so picture this: you're deep in the kernel, specifically in ./drivers/net/phy/phylink.c, and you've got a speed and a duplex just sitting there and you need the mac capability. yeah. that's the whole plot. this page is from the Kernel API Manual, section 9, and it's genuinely a little icon. ✨

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🌸 NAME 🌸

phylink_cap_from_speed_duplex — bestie, this gets you the mac capability from speed/duplex. that's it. that's the function. no cap. 💖

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✨ SYNOPSIS ✨

unsigned long phylink_cap_from_speed_duplex (int speed , unsigned int duplex );

she returns an unsigned long, she takes two args, she's booked and busy. 🫶

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🦋 ARGUMENTS 🦋

• speed — the speed to search for 👀 like the number, the velocity, the vibe
• duplex — the duplex to search for 🔥 (it's an unsigned int, fyi)

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💜 DESCRIPTION 💜

literally so simple: find the mac capability for a given speed and duplex. you hand it speed, you hand it duplex, it goes looking, it finds the mac capability. main character energy from a one-line function, honestly. 🌟

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👑 RETURN 👑

you get back a mask with the mac capability patching speed and duplex 💅 — or 0 if there were no matches. and yes, 0 means nothing matched, so don't go treating it like a real capability, bestie. 😭

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🌈 SEE ALSO 🌈

the whole group chat, fr fr — start with the kernel file itself:

Kernel file ./drivers/net/phy/phylink.c

then the crew:

• struct phylink(9)
• phylink_set_port_modes(9)
• phylink_interface_max_speed(9)
• phylink_caps_to_link_caps(9)
• phylink_caps_to_linkmodes(9)
• phylink_limit_mac_speed(9)
• phylink_get_capabilities(9)
• phylink_validate_mask_caps(9)
• phylink_pcs_neg_mode(9)
• phylink_set_fixed_link(9)
• phylink_create(9)
• phylink_destroy(9)
• phylink_expects_phy(9)
• phylink_connect_phy(9)
• phylink_of_phy_connect(9)
• phylink_fwnode_phy_connect(9)
• phylink_disconnect_phy(9)
• phylink_mac_change(9)
• phylink_pcs_change(9)
• phylink_start(9)
• phylink_stop(9)
• phylink_rx_clk_stop_block(9)
• phylink_rx_clk_stop_unblock(9)
• phylink_suspend(9)
• phylink_prepare_resume(9)
• phylink_resume(9)
• phylink_ethtool_get_wol(9)
• phylink_ethtool_set_wol(9)
• phylink_ethtool_ksettings_get(9)
• phylink_ethtool_ksettings_set(9)
• phylink_ethtool_nway_reset(9)
• phylink_ethtool_get_pauseparam(9)
• phylink_ethtool_set_pauseparam(9)
• phylink_get_eee_err(9)
• phylink_ethtool_get_eee(9)
• phylink_ethtool_set_eee(9)
• phylink_mii_ioctl(9)
• phylink_speed_down(9)
• phylink_speed_up(9)
• phylink_decode_usxgmii_word(9)
• phylink_decode_usgmii_word(9)
• phylink_mii_c22_pcs_decode_state(9)
• phylink_mii_c22_pcs_get_state(9)
• phylink_mii_c22_pcs_encode_advertisement(9)
• phylink_mii_c22_pcs_config(9)
• phylink_mii_c22_pcs_an_restart(9)
• phylink_replay_link_begin(9)
• phylink_replay_link_end(9)

like i said. the whole group chat. 47 links and every single one is invited. 🧚‍♀️

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ngl the only real gotcha here is the 0 return — no match means no capability mask, so check it before you assume you've got something. 🫡

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okay that's the whole page!! 💖 this one's brought to you by ./drivers/net/phy, dated October 2026, and it's literally phylink_cap...speed_duplex(9) from the Kernel API Manual — slay, go read your manpages, ily, bye 🎀🦋✨