drm_sysfb_build_fourcc_list(9)

✨ drm_sysfb_build_fourcc_list 💅

okay so bestie, welcome to the drm_sysfb_build_fourcc_list(9) page of the Kernel API Manual — yes that's the manual name, and yes we're diving straight in because this one's actually kind of a bop 🎀

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🌸 NAME 🌸

drm_sysfb_build_fourcc_list — it filters a list of supported color formats against the device's native formats, no cap ✨

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🦋 SYNOPSIS 🦋

size_t drm_sysfb_build_fourcc_list (struct drm_device *dev , const u32
*native_fourccs , size_t native_nfourccs , u32 *fourccs_out , size_t
nfourccs_out );

like, that's the whole signature, take it in, it's giving function 💜

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🎀 ARGUMENTS 🎀

• dev — the DRM device itself, the main character 👑
• native_fourccs — the 4CC codes of natively supported color formats 🖼️
• native_nfourccs — the number of entries in native_fourccs, literally just the count 🧮
• fourccs_out — where the 4CC codes of supported color formats get returned to you 🫶
• nfourccs_out — the number of available entries in fourccs_out, so it knows how much room it's got 🌸

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💖 DESCRIPTION 💖

So this function creates a list of supported color formats from the natively supported formats plus some additional emulated formats. periodt ✨

At a minimum, most userspace programs expect at least support for XRGB8888 on the primary plane — that's the floor, bestie, don't go below it 😭

Sysfb devices that have to emulate the format should use drm_sysfb_build_fourcc_list to create a list of supported color formats. The returned list can be handed over to drm_universal_plane_init et al. — yes, "et al.", very fancy 💅

Now the important ranking tea ☕:

• Native formats will go before emulated formats. native stays winning 🥇
• Native formats with an alpha channel will be replaced by equal formats without an alpha channel, because primary planes usually don't support alpha 🙈
• Other heuristics might be applied to optimize the sorting order — so the order isn't totally fixed, iykyk 🤫
• Formats near the beginning of the list are usually preferred over formats near the end of the list. front of the line = main character energy 🔥

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⭐ RETURN ⭐

It returns the number of color-formats 4CC codes returned in fourccs_out. that's it, that's the return value, slay 💫

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🌈 SEE ALSO 🌈

• Kernel file ./drivers/gpu/drm/sysfb/drm_sysfb_modeset.c — go read it, it's right there 🦋

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💀 heads up: the sorting order involves heuristics, so "might be applied" means might — don't go assuming a guaranteed order beyond what's written here, fr fr.

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and that's the page!! brought to you by ./drivers/gpu/drm/sysfb, dated October 2026 — mwah, go build those fourcc lists bestie 🫶💖✨