brcmf_setup_ifmodes(9)

💅 brcmf_setup_ifmodes — a Kernel API Manual moment

okay so bestie, we're in the kernel API manual today and the star of the show is brcmf_setup_ifmodes(9). yes it's a mouthful, no you don't have to say it out loud at parties. it lives in the kernel docs, it's giving driver-internals realness, and honestly? it ate. let's get into it 🎀

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✨ NAME ✨

brcmf_setup_ifmodes — figure out which interface modes you get, and which combos of them are allowed. that's the whole job. slay 🫶

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🌸 SYNOPSIS 🌸

int brcmf_setup_ifmodes (struct wiphy *wiphy , struct brcmf_if *ifp );

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🦋 ARGUMENTS 🦋

• wiphy — the wiphy object. yes, that one. the wireless phy dude.
• ifp — the interface object, and it's needed specifically for the feat module api. don't forget it, bestie, it's kind of the whole point 🙈

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👑 DESCRIPTION 👑

so the interface modes AND their combinations get determined dynamically right here, based on what the firmware can actually do. no hardcoded little list, nope, it's a vibe check against the firmware's feature set. iconic behavior honestly ✨

here's how the combos shake out, depending on what the firmware's got going on:

💀 no p2p and no mbss

#STA <= 1, #AP <= 1, channels = 1, 2 total

that's it. that's the whole menu. one STA max, one AP max, one channel, two total. minimal. cozy. 🍓

🔥 no p2p and mbss

#STA <= 1, #AP <= 1, channels = 1, 2 total #AP <= 4, matching BI, channels = 1, 4 total

okay so we've got the #STA <= 1, #AP <= 1, channels = 1, 2 total situation, and then #AP <= 4, matching BI, channels = 1, 4 total on top of that. matching BI, bestie. matching. BI. 😤

🌈 no p2p and rsdb

#STA <= 1, #AP <= 2, channels = 2, 4 total

one STA, up to two APs, two channels, four total. rsdb said "let me give you range" fr fr 💜

⭐ p2p, no mchan, and mbss

#STA <= 1, #P2P-DEV <= 1, #{P2P-CL, P2P-GO} <= 1, channels = 1, 3 total
#STA <= 1, #P2P-DEV <= 1, #AP <= 1, #P2P-CL <= 1, channels = 1, 4 total
#AP <= 4, matching BI, channels = 1, 4 total

three whole combos, and yes the third one is that matching BI legend again. we love consistency 👑

🧚 p2p, mchan, and mbss

#STA <= 2, #P2P-DEV <= 1, #{P2P-CL, P2P-GO} <= 1, channels = 2, 3 total
#STA <= 1, #P2P-DEV <= 1, #AP <= 1, #P2P-CL <= 1, channels = 1, 4 total
#AP <= 4, matching BI, channels = 1, 4 total

mchan enters the chat and suddenly #STA <= 2 and channels = 2 are on the table. glow up 💅

🌸 p2p, rsdb, and no mbss

#STA <= 1, #P2P-DEV <= 1, #{P2P-CL, P2P-GO} <= 2, AP <= 2, channels = 2, 4 total

note that it's AP <= 2 here and not #AP — that's literally how it's written, so that's literally how we're writing it. no cap, character for character 🫶

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🎀 RETURN 🎀

0 on success, negative errno on failure. so like, if you get a negative back, something went sideways and it's telling you why in errno form. read it. it's trying to communicate 😭

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🍓 SEE ALSO 🍓

• Kernel file: ./drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
• brcmf_apsta_add_vif(9)
• brcmf_mon_add_vif(9)

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heads up bestie: the source line at the bottom of the original got truncated mid-path (./drivers/net/wireless/broadco...), and the date on it is October 2026. that's the version/date stamp, not a typo on my end 💖

k that's the whole page!! go read cfg80211.c, it's right there, i believe in you. mwah 💋 ✨