REG_FIELD_PREP(9)

💅 REG_FIELD_PREP(9) — like, the Kernel API Manual one, bestie

okay so picture this: you're deep in the kernel, you've got a u32 bitfield, and you need a value prepared for it. That's literally the whole gig. Welcome to REG_FIELD_PREP from the Kernel API Manual, she's iconic, she's in ./include/drm/intel/reg_bits.h, let's go ✨

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✨ SYNOPSIS ✨

REG_FIELD_PREP (__mask , __val );

two args, no drama 🎀

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🌸 ARGUMENTS 🌸

• __mask — the shifted mask, bestie. It's the thing that defines your field's length and its position. mask is the blueprint, fr fr.
• __val — the actual value you're putting in that field. the main character of the operation 👑

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💖 DESCRIPTION 💖

so this is a local copy of FIELD_PREP — yes, a copy, we live here now — and it exists to do three very specific things, no cap:

1. generate an integer constant expression,
2. force u32, because we said so,
3. stay consistent with REG_FIELD_GET, REG_BIT and REG_GENMASK. the friend group has to match, obviously 🫶

that's it, that's the vibe check. 💅

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🔥 RETURN 🔥

__val — but masked and shifted into the field defined by __mask. so it comes back all glowed-up and field-shaped. slay.

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🌈 SEE ALSO 🌈

all of these live in the kernel file ./include/drm/intel/reg_bits.h, and they're all in the group chat:

• REG_FIELD_PREP8(9)
• REG_FIELD_PREP16(9)
• REG_FIELD_GET8(9)
• REG_FIELD_GET(9)
• REG_FIELD_GET64(9)
• REG_FIELD_MAX(9)

go read them, iykyk 💜

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ngl this page is short and sweet and that's the point — don't overthink it, just mask and shift 🦋

okay bye, this page was brought to you by <pink>./include/drm/intel</pink> in <purple>October 2026</purple> — mwah, take care of her 💖🎀✨