docs: add displayport audio desync page with the dcn201 spread-spectrum root cause#35
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…um root cause The DP audio desync/delay/crackle only had the active-adapter hand-wave in display.md. This adds a dedicated troubleshooting/audio.md documenting the real root cause: dcn201_clk_mgr applies the shared GPU-clock spread spectrum to the DP reference clock, ignoring the VBIOS dp_ss_control=0. Verified against mainline source. Corrects the resolved-in-6.19.10 claim: that is downstream only, mainline 7.1.x still calls dce_clock_read_ss_info unconditionally. Diagnostic commands tested live on the board. Trov's dcn201 patch is shown but flagged as not verified on our board. Refs the BC-250 Discord audio thread (Trov, essdee, mzk10).
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Trov here - this version of the kernel patch doesn't work. I assumed that the VBIOS was setting dp_ss_control to 0, because it's what's in BIOS chip. |
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What's in this PR
troubleshooting/audio.md: the DisplayPort audio desync/delay/crackle root cause (DCN201 spread-spectrum bug), diagnosis, and the fix.dce_clock_read_ss_info()unconditionally, so it is still affected. Verified against the mainline source.display.md(the SS desync is a separate, kernel-level issue from the active-adapter re-encode one).mkdocs.yml.Why this and not more
display.mdactive-adapter content intact and only added a cross-reference, since the two issues are distinct.