drm_test_bri...n_verify_fmt(9)

💅 drm_test_bri...n_verify_fmt(9) — the kernel API manual, but make it make sense 🫶

okay so bestie, this is a section 9 kernel API page. the full name is a whole mouthful that got squished to drm_test_bri...n_verify_fmt(9) in the header, but the real one is drm_test_bridge_chain_verify_fmt. say it with me. slay. ✨

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🦋 NAME 🦋

drm_test_bridge_chain_verify_fmt — literally just verifying bridge chain format selection. that's the whole vibe check. 💅

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🎀 SYNOPSIS 🎀

void drm_test_bridge_chain_verify_fmt (struct kunit *test , struct
drm_bridge_chain_priv *priv , const struct fmt_tuple *const expected ,
const unsigned int num_expected );

copy it exactly, no cap, don't retype it from memory. 😭

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🌸 ARGUMENTS 🌸

• test — pointer to the KUnit test object. yes, the test thingy. it's how kunit knows which test is doing the shouting. 🧚
• priv — pointer to a struct drm_bridge_chain_priv for this chain. like, the specific chain, not a random one, bestie. 👑
• expected — a constant array of struct fmt_tuple that describes the expected input and output bus formats. this is the "what should have happened" list. ⭐
• num_expected — the number of entries in expected. yeah. it's the count. if you lie about the count the vibes will be off. 💀

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🔥 DESCRIPTION 🔥

so what does it actually do? it runs the KUNIT_EXPECT clauses to verify that the bridge chain format selection resulted in the expected formats. that's it. that's the function. no cap. ✨

and here's the iconic little detail: if 0 is given as a format in a struct fmt_tuple, then it is understood to mean "any". so 0 = wildcard = "i don't care, whatever format, live your truth". 🌈

⚠️ ok important one, don't skip this: must be called with the modeset lock held. like, fr fr. not optional. hold the lock, bestie. 🫶

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🍓 SEE ALSO 🍓

• Kernel file ./drivers/gpu/drm/tests/drm_bridge_test.c — go read the source, iykyk 📖
• struct fmt_tuple(9) — the struct doing all the work 💜
• get_tuples_out_fmts(9) — its bestie 🦋

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💖 sign-off 💖

this masterpiece lives under ./drivers/gpu/drm/tests, and it's stamped October 2026 — dated, sourced, and absolutely iconic. periodt. 🎀✨👑