sg2042_pll_get_postdiv_1_2(9)

💖 sg2042_pll_get_postdiv_1_2(9) 💖

okay so bestie, welcome to the Kernel API Manual — yes this is that Kernel API Manual — and today's main character is a PLL helper that just wants to find you the right divider combo. no cap. 🫶

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✨ NAME ✨

sg2042_pll_get_postdiv_1_2 — literally takes your input rate/prate/fbdiv/refdiv, looks up the postdiv1_2 table, and gets you the closest postdiiv combination. (and yes, "postdiiv" is spelled exactly like that in the source material, i'm not fixing it, it's iconic 💀)

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🦋 SYNOPSIS 🦋

int sg2042_pll_get_postdiv_1_2 (unsigned long rate , unsigned long prate
, unsigned int fbdiv , unsigned int refdiv , unsigned int *postdiv1 ,
unsigned int *postdiv2 );

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🎀 ARGUMENTS 🎀

• rate — the FOUTPOSTDIV. the output vibe you're aiming for. ⭐
• prate — the parent rate, a.k.a. FREF. where you're coming from, bestie.
• fbdiv — the FBDIV. keep it, don't lose it. 💅
• refdiv — the REFDIV. the reference divider of the group.
• postdiv1 — POSTDIV1, and it's an output. so this pointer gets filled in, not read. 🙈
• postdiv2 — POSTDIV2, also an output. same deal, pointer goes out. 🌸

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🔥 DESCRIPTION 🔥

postdiv1_2 is holding all the possible combination lists of POSTDIV1 and POSTDIV2 — like, the whole roster. for example:

postdiv1_2[0] = {2, 4, 8}, where div1 = 2, div2 = 4 , div1 * div2 = 8

so in that one, div1 = 2, div2 = 4, and div1 * div2 = 8. math ate, honestly. ✨

See TRM: FOUTPOSTDIV = FREF * FBDIV / REFDIV / (POSTDIV1 * POSTDIV2)

so from that we get the following formula to get POSTDIV1 and POSTDIV2:

POSTDIV = (prate/REFDIV) x FBDIV/rate

and, above, POSTDIV = POSTDIV1*POSTDIV2. periodt. 👑

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💀 RETURN 💀

• 0 — okay! OK. we slayed, everything worked. 🎉
• -EINVAL — invalid argument, which means it failed to get the postdivs. sad girl hours. 😭

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🌈 SEE ALSO 🌈

• kernel file ./drivers/clk/sophgo/clk-sg2042-pll.c
• struct sg2042_pll_clock(9)
• sg2042_pll_recalc_rate(9)
• sg2042_get_pll_ctl_setting(9)
• sg2042_clk_pll_recalc_rate(9)

all of these are lowkey part of the same friend group, go say hi. 🫶

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and that's the whole page, bestie! this one came to you from ./drivers/clk/sophgo, dated October 2026 — the source/version and the date are right there, folded into this cute little sign-off instead of a boring footer line. mwah 💋 sg2042_pll_get_postdiv_1_2(9) out. 💅🎀