Files
Harry Wentland cafa53d327 drm/amd/display: Fix dcn32 DTB DTO update breaking live pixel rate sources
commit 76a2db58e9 upstream.

dcn32_update_clocks_update_dtb_dto() reprograms the DTB DTO of every
timing generator in the context whenever the DTBCLK reference changes,
passing a zeroed pixel rate and never setting is_hdmi.
dccg32_set_dtbclk_dto() treats a zero pixel rate as a disable request,
and that branch drives PIPE_DTO_SRC_SEL to the DP DTO source. A timing
generator actively scanning out an HDMI stream therefore has its pixel
rate source re-muxed out from under the live raster, and the OTG stops
on the spot.

Two displays where only one runs a 128b/132b link hit this reliably.
is_dtbclk_required() holds the DTBCLK reference high while both are
active, and the moment the 128b/132b stream is torn down (compositor
switch, display disable, hot-unplug) the next safe_to_lower pass drops
the reference to the lowest DPM level and the DTO walk freezes the
surviving screen. On Navi31 the DAL mailbox then goes deaf on the
DISPCLK hard-min that follows the walk in dcn32_update_clocks(),
stranding both SMU mailboxes until reboot.

Set is_hdmi for HDMI and DVI signals so the disable path leaves the
pixel rate source selection on the HDMI path, and pass the real pixel
rate for 128b/132b streams so a reference change rescales their DTO
instead of disabling it.

Fixes: 128c1ca030 ("drm/amd/display: Update DTBCLK for DCN32")
Signed-off-by: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: Fangzhi Zuo <Jerry.Zuo@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
[ mschwartz: dcn32 clk_mgr hunk only, as 6.6.y predates the dcn35
  clk_mgr. The rest is HDMI FRL enablement, absent before 7.2, so the
  FRL conditions and the req_audio_dtbclk_khz assignment they guard are
  dropped and the FRL-centric changelog is rewritten. Added the
  pipe_ctx->stream check the new dereferences need. ]
Signed-off-by: Matthew Schwartz <matthew.schwartz@linux.dev>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2026-08-03 11:15:33 +02:00
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