[PATCH 6.18 176/752] drm/amd/display: Ensure link output is disabled in backend reset for PLL_ON

Sasha Levin
2026-02-28T17:50:38Z

From: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>

[ Upstream commit 4589712e0111352973131bad975023b25569287c ]

[Why]
We're missing the code to actually disable the link output when we have
to leave the SYMCLK_ON but the TX remains OFF.

[How]
Port the code from DCN401 that detects SYMCLK_ON_TX_OFF and disable
the link output when the backend is reset.

Reviewed-by: Ovidiu (Ovi) Bunea <ovidiu.bunea@amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Matthew Stewart <matthew.stewart2@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
.../drm/amd/display/dc/hwss/dcn31/dcn31_hwseq.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/hwss/dcn31/dcn31_hwseq.c b/drivers/gpu/drm/amd/display/dc/hwss/dcn31/dcn31_hwseq.c
index b822f2dffff0e..e9bd43a72ce58 100644
--- a/drivers/gpu/drm/amd/display/dc/hwss/dcn31/dcn31_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/hwss/dcn31/dcn31_hwseq.c
@@ -546,8 +546,22 @@ static void dcn31_reset_back_end_for_pipe(
if (pipe_ctx->stream_res.tg->funcs->set_odm_bypass)
pipe_ctx->stream_res.tg->funcs->set_odm_bypass(
pipe_ctx->stream_res.tg, &pipe_ctx->stream->timing);
+ /*
+ * TODO - convert symclk_ref_cnts for otg to a bit map to solve
+ * the case where the same symclk is shared across multiple otg
+ * instances
+ */
if (dc_is_hdmi_tmds_signal(pipe_ctx->stream->signal))
- pipe_ctx->stream->link->phy_state.symclk_ref_cnts.otg = 0;
+ link->phy_state.symclk_ref_cnts.otg = 0;
+
+ if (pipe_ctx->top_pipe == NULL) {
+ if (link->phy_state.symclk_state == SYMCLK_ON_TX_OFF) {
+ const struct link_hwss *link_hwss = get_link_hwss(link, &pipe_ctx->link_res);
+
+ link_hwss->disable_link_output(link, &pipe_ctx->link_res, pipe_ctx->stream->signal);
+ link->phy_state.symclk_state = SYMCLK_OFF_TX_OFF;
+ }
+ }

set_drr_and_clear_adjust_pending(pipe_ctx, pipe_ctx->stream, NULL);

--
2.51.0