drm_hdmi_acr_get_n_cts(9)

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

okay so this is a page from the Kernel API Manual, and it's about drm_hdmi_acr_get_n_cts — a little function that pulls the N and CTS values for Audio Clock Regeneration, and honestly? it's giving unsung hero energy. ✨

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🌸 NAME 🌸

drm_hdmi_acr_get_n_cts — get N and CTS values for Audio Clock Regeneration 💖

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✨ SYNOPSIS ✨

void drm_hdmi_acr_get_n_cts (unsigned long long tmds_char_rate ,
       unsigned int sample_rate , unsigned int *out_n , unsigned int *out_cts
);

like, yes, that's the whole signature. no cap, she's void — she doesn't return anything, she writes through your pointers. main character behavior tbh 🫶

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🦋 ARGUMENTS 🦋

• tmds_char_rate — the TMDS clock (char rate) exactly as it's used by the HDMI connector. yes, unsigned long long, she's a big girl 💅
• sample_rate — the audio sample rate. that's the Fs vibe, more on that below 👀
• out_n — a pointer where the N value gets written 🎀
• out_cts — a pointer where the CTS value gets written ⭐

lowkey important: out_n and out_cts are pointers you pass in, and the function writes into them. that's how you get your data back out, since the return type is void. 💀

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🌈 DESCRIPTION 🌈

so what does she actually do? she gets the N and CTS values — either by calculating them, or by returning data straight out of the tables. either way, you get your numbers. obsessed. 🔥

this all follows the HDMI 1.4b Section 7.2 "Audio Sample Clock Capture and Regeneration" — so if you wanna fact-check her, that's the homework. 📚

and heads up, bestie: sample_rate corresponds to the Fs value. see sections 7.2.4 – 7.2.6 for how to select Fs for non-L-PCM formats. like, don't just assume — go read those sections, iykyk 🙈

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💜 SEE ALSO 💜

• Kernel file ./drivers/gpu/drm/display/drm_hdmi_helper.c — that's where the magic lives 🧚
• drm_hdmi_infoframe_set_hdr_metadata(9)
• drm_hdmi_avi_infoframe_colorimetry(9)
• drm_hdmi_avi_infoframe_bars(9)
• drm_hdmi_avi_infoframe_content_type(9)
• drm_hdmi_compute_mode_clock(9)

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and that's the whole page, periodt. 💖 this lil slice of the kernel API manual comes from ./drivers/gpu/drm/display, dated October 2026 — so go forth, pass your pointers, and slay those N and CTS values. 👑🌸