drm/amd/display: rework recent update PHY state commit

[why]
Original change 594b237b9a07 ("drm/amd/display: Add
interface to track PHY state") was implemented by assuming stream's
dpms off is equivalent to PHY power off.
This assumption doesn't hold in following situations:
1. MST multiple stream scenario, where multiple streams are sharing the
same PHY output. Toggle dpms off for one of the stream doesn't power
off the PHY due to the presence of other streams.
2. enable stream failure scenario, where enable stream fails due to
failure of link training. This will cause DPMS off is set to false, while
the actual PHY power state is off in certain cases.
Due to the problematic assumption, the logic will skip disabling
other streams for MST multiple stream scenario, therefore PHY is
not actually powered off.

[how]
1. Rework this refactor by moving PHY state update down to hardware
level, where we update PHY state in place when hardware sequencer
is actually changing the power state of the PHY hardware.
2. Reimplement symclk on TX off workaround in place when we are actually
calling transmitter control to power off PHY in dcn32. Note the workaround is
added due to the lack of proper software interface to set TX while keeping
symclk on. We plan to address this interface problem so we can set TX off
only without affecting symclk in future dcn versions.

Fixes: 594b237b9a07 ("drm/amd/display: Add interface to track PHY state")
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Wayne Lin <wayne.lin@amd.com>
Signed-off-by: Wenjing Liu <wenjing.liu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/display/dc/virtual/virtual_link_hwss.c b/drivers/gpu/drm/amd/display/dc/virtual/virtual_link_hwss.c
index 501173ce270e..9522fe0b36c9 100644
--- a/drivers/gpu/drm/amd/display/dc/virtual/virtual_link_hwss.c
+++ b/drivers/gpu/drm/amd/display/dc/virtual/virtual_link_hwss.c
@@ -36,10 +36,18 @@ void virtual_setup_stream_attribute(struct pipe_ctx *pipe_ctx)
 void virtual_reset_stream_encoder(struct pipe_ctx *pipe_ctx)
 {
 }
+
+void virtual_disable_link_output(struct dc_link *link,
+	const struct link_resource *link_res,
+	enum signal_type signal)
+{
+}
+
 static const struct link_hwss virtual_link_hwss = {
 	.setup_stream_encoder = virtual_setup_stream_encoder,
 	.reset_stream_encoder = virtual_reset_stream_encoder,
 	.setup_stream_attribute = virtual_setup_stream_attribute,
+	.disable_link_output = virtual_disable_link_output,
 };
 
 const struct link_hwss *get_virtual_link_hwss(void)