calculate_sw...deadline_dst(9)

💅 NAME

ok so bestie, this is calculate_swath_deadline_dst — it's the little helper function that does the math for you and spits out the hdl dst position when you hand it a swath index ✨ (yes, that's literally the whole job, and it ate)

This page lives in section 9 of the Kernel API Manual, and yeah the title is a whole mouthful: calculate_sw...deadline_dst(9) 🎀

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🌸 SYNOPSIS

no cap, here's the exact signature, copy it character for character or it won't vibe:

uint32_t calculate_swath_deadline_dst (uint32_t swath_index , uint32_t
prefetch_swaths , uint32_t pre_first_hdl_x1000 , uint32_t
rec_first_hdl_x1000 , uint32_t pre_hdl_delta_x1000 , uint32_t
rec_hdl_delta_x1000 );

like, it returns a uint32_t and takes six uint32_ts. six. iconic of it honestly 💜

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🦋 ARGUMENTS

ok so this is the part where the docs simply did not show up 😭 every single one of these is marked -- undescribed -- in the original. i'm not gonna invent lore, that would be lying to you and we don't do that here 🙈 so here's the full roster, exactly as mysterious as the source left it:

• swath_index — -- undescribed -- (mystery girl. unknown. we simply don't know.)
• prefetch_swaths — -- undescribed -- (also undescribed, the silence is loud)
• pre_first_hdl_x1000 — -- undescribed -- (undescribed, but the name has _x1000 in it which is giving fixed-point energy, iykyk)
• rec_first_hdl_x1000 — -- undescribed -- (same situation, still undescribed)
• rec_first_hdl_delta_x1000 — -- undescribed -- (undescribed, delta flavored)
• rec_hdl_delta_x1000 — -- undescribed -- (last one, also undescribed, we stan a consistent absence 💀)

fr fr: don't guess at these semantics. the manpage literally left them blank. if you need to know, go read the source, bestie 🫶

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✨ RETURN

it hands you back the dst line associated with the swath deadline ⭐ that's the value, that's the whole return, go off king 👑

aaand then the original just drops this absolute unit of a separator line at the end of the RETURN section, so here it is in all its glory, verbatim, we do not gatekeep:

***********************************************************************************************************

like… 107 asterisks of pure main character energy. obsessed. 🔥

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🌈 SEE ALSO

ok the cross-reference situation is stacked, bestie. first, the kernel file this thing lives in — full path, no cuts:

./drivers/gpu/drm/amd/display/dc/dml2_0/dml21/src/dml2_standalone_libraries/alternate_pstate_shared_lib.c

and then the whole friend group, all in section 9, in this exact order:

• in_circular_range(9)
• apply_svp1_workaround(9)
• calculate_start_line_and_height_from_swath(9)
• get_swath_deadlines(9)
• is_dst_in_next_frame(9)
• is_end_swath_in_next_frame(9)
• is_svp_dst_in_next_frame(9)
• calculate_swath_idx_from_dst(9)
• populate_svp_params(9)
• populate_start_index_num_swaths_helper(9)
• calculate_start_index_num_swaths(9)
• calculate_hubp_start_end_lines(9)
• get_prefetch_end_line(9)
• get_effective_vblank_start(9)

that's fourteen besties plus the file. a whole group chat 🧚

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🎀 sign-off

this page came from the source path ./drivers/gpu/drm/amd/display/... and the version/date stamp on it is October 2026, stamped with the title calculate_sw...deadline_dst(9) at the bottom like a little signature. slay, bye, go read the source 💖🌸💅