calculate_st...x_num_swaths(9)

💅 calculate_st...x_num_swaths(9) — Kernel API Manual 💅

okay so bestie, welcome to the Kernel API Manual page for calculate_start_index_num_swaths. it’s giving helper-function main character energy, and we’re gonna read it together. 🫶✨

🌸 NAME 🌸

calculate_start_index_num_swaths — the helper function that calculates svp params for both vp0 and vp1. that’s the whole vibe, no cap. 💖

🦋 SYNOPSIS 🦋

void calculate_start_index_num_swaths (uint32_t svp0_start_swath_idx ,
uint32_t svp0_end_swath_idx , uint32_t svp1_start_swath_idx , uint32_t
svp1_end_swath_idx , uint16_t prefetch_swaths , uint16_t total_swaths ,
uint32_t *svp0_start_sw_idx_curr , uint32_t *svp0_num_swaths_curr ,
uint32_t *svp0_start_sw_idx_next , uint32_t *svp0_num_swaths_next ,
uint32_t *svp1_start_sw_idx_curr , uint32_t *svp1_num_swaths_curr ,
uint32_t *svp1_start_sw_idx_next , uint32_t *svp1_num_swaths_next );

🎀 ARGUMENTS 🎀

okay so there are 14 arguments, and the source is out here giving us absolutely nothing but -- undescribed -- for every single one. not me reading the manual like 👁️👄👁️. anyway, here they all are, exactly, with zero invented lore:

• svp0_start_swath_idx — -- undescribed --
• svp0_end_swath_idx — -- undescribed --
• svp1_start_swath_idx — -- undescribed --
• svp1_end_swath_idx — -- undescribed --
• prefetch_swaths — -- undescribed --
• total_swaths — -- undescribed --
• svp0_start_sw_idx_curr — -- undescribed --
• svp0_num_swaths_curr — -- undescribed --
• svp0_start_sw_idx_next — -- undescribed --
• svp0_num_swaths_next — -- undescribed --
• svp1_start_sw_idx_curr — -- undescribed --
• svp1_num_swaths_curr — -- undescribed --
• svp1_start_sw_idx_next — -- undescribed --
• svp1_num_swaths_next — -- undescribed --

bestie, the manual literally says -- undescribed -- for all of these, so I’m not gonna guess at behaviour. that would be fake lore and we don’t do that here. 💅

🔥 DESCRIPTION 🔥

okay so the actual description is short and sweet: it calculates svp parameters in terms of start swath idx and number of swaths for both vp0 and vp1. lowkey iconic that it does both vp0 and vp1. 💜

there’s also this exact asterisk wall in the page, so I’m preserving it because details matter:

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

🌈 SEE ALSO 🌈

first up, Kernel file: ./drivers/gpu/drm/amd/display/dc/dml2_0/dml21/src/dml2_standalone_libraries/alternate_pstate_shared_lib.c

then the whole bestie squad of refs, all present and accounted for:

• in_circular_range(9)
• apply_svp1_workaround(9)
• calculate_start_line_and_height_from_swath(9)
• get_swath_deadlines(9)
• calculate_swath_deadline_dst(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_hubp_start_end_lines(9)
• get_prefetch_end_line(9)
• get_effective_vblank_start(9)

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mwah 💋 this page is from ./drivers/gpu/drm/amd/display/... and it’s dated October 2026, bestie. go off and calculate those svp params. periodt. 🎀✨🦋