[PATCH 5.13 024/127] drm/amd/display: workaround for hard hang on HPD on native DP

Sasha Levin
2021-08-24T16:57:28Z

From: Qingqing Zhuo <qingqing.zhuo@amd.com>

[ Upstream commit c4152b297d56d3696ad0a9003169bc5b98ad7b72 ]

[Why]
HPD disable and enable sequences are not mutually exclusive
on Linux. For HPDs that spans over 1s (i.e. HPD low = 1s),
part of the disable sequence (specifically, a request to SMU
to lower refclk) could come right before the call to PHY
enable, causing DMUB to access an unresponsive PHY
and thus a hard hang on the system.

[How]
Disable 48mhz refclk off on native DP.

Reviewed-by: Hersen Wu <hersenxs.wu@amd.com>
Acked-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/amd/display/dc/clk_mgr/dcn21/rn_clk_mgr.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn21/rn_clk_mgr.c b/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn21/rn_clk_mgr.c
index 75ba86f951f8..7bbedb6b4a9e 100644
--- a/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn21/rn_clk_mgr.c
+++ b/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn21/rn_clk_mgr.c
@@ -66,9 +66,11 @@ int rn_get_active_display_cnt_wa(
for (i = 0; i < context->stream_count; i++) {
const struct dc_stream_state *stream = context->streams[i];

+ /* Extend the WA to DP for Linux*/
if (stream->signal == SIGNAL_TYPE_HDMI_TYPE_A ||
stream->signal == SIGNAL_TYPE_DVI_SINGLE_LINK ||
- stream->signal == SIGNAL_TYPE_DVI_DUAL_LINK)
+ stream->signal == SIGNAL_TYPE_DVI_DUAL_LINK ||
+ stream->signal == SIGNAL_TYPE_DISPLAY_PORT)
tmds_present = true;
}

--
2.30.2