[PATCH] drm/amd/display: Fix DVI-D/HDMI adapters

[Timur Kristóf]

When the EDID has the HDMI bit, we should simply select
the HDMI signal type even on DVI ports.

For reference see, the legacy amdgpu display code:
amdgpu_atombios_encoder_get_encoder_mode
which selects ATOM_ENCODER_MODE_HDMI for the same case.

This commit fixes DVI connectors to work with DVI-D/HDMI
adapters so that they can now produce output over these
connectors for HDMI monitors with higher bandwidth modes.
With this change, even HDMI audio works through DVI.

For testing, I used a CAA-DMDHFD3 DVI-D/HDMI adapter
with the following GPUs:

Tahiti (DCE 6) - DC can now output 4K 30 Hz over DVI
Polaris 10 (DCE 11.2) - DC can now output 4K 60 Hz over DVI

Signed-off-by: Timur Kristóf <timur.kristof at gmail.com>
---
 drivers/gpu/drm/amd/display/dc/link/link_detection.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/dc/link/link_detection.c b/drivers/gpu/drm/amd/display/dc/link/link_detection.c
index 827b630daf49..42180e6aca91 100644
--- a/drivers/gpu/drm/amd/display/dc/link/link_detection.c
+++ b/drivers/gpu/drm/amd/display/dc/link/link_detection.c
@@ -1140,6 +1140,10 @@ static bool detect_link_and_local_sink(struct dc_link *link,
 		if (sink->sink_signal == SIGNAL_TYPE_HDMI_TYPE_A &&
 		    !sink->edid_caps.edid_hdmi)
 			sink->sink_signal = SIGNAL_TYPE_DVI_SINGLE_LINK;
+		else if (dc_is_dvi_signal(sink->sink_signal) &&
+			aud_support->hdmi_audio_native &&
+			sink->edid_caps.edid_hdmi)
+			sink->sink_signal = SIGNAL_TYPE_HDMI_TYPE_A;
 
 		if (link->local_sink && dc_is_dp_signal(sink_caps.signal))
 			dp_trace_init(link);
-- 
2.50.1