drm/amd/display: Remove OTG DIV register write for Virtual signals.

[ Upstream commit 709671ffb15dcd1b4f6afe2a9d8c67c7c4ead4a1 ]

[WHY]
Hot plugging and then hot unplugging leads to k1 and k2 values to
change, as signal is detected as a virtual signal on hot unplug. Writing
these values to OTG_PIXEL_RATE_DIV register might cause primary display
to blank (known hw bug).

[HOW]
No longer write k1 and k2 values to register if signal is virtual, we
have safe guards in place in the case that k1 and k2 is unassigned so
that an unknown value is not written to the register either.

Cc: stable@vger.kernel.org
Cc: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Samson Tam <Samson.Tam@amd.com>
Reviewed-by: Alvin Lee <Alvin.Lee2@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Saaem Rizvi <SyedSaaem.Rizvi@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_hwseq.c b/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_hwseq.c
index f108e82e70c8b9197b3c4f044557dd76079b0770..1a85509c12f23a5d94eea9bbf2f6f53ef04cc26a 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_hwseq.c
@@ -1180,7 +1180,7 @@ unsigned int dcn32_calculate_dccg_k1_k2_values(struct pipe_ctx *pipe_ctx, unsign
                        *k2_div = PIXEL_RATE_DIV_BY_2;
                else
                        *k2_div = PIXEL_RATE_DIV_BY_4;
-       } else if (dc_is_dp_signal(stream->signal) || dc_is_virtual_signal(stream->signal)) {
+       } else if (dc_is_dp_signal(stream->signal)) {
                if (two_pix_per_container) {
                        *k1_div = PIXEL_RATE_DIV_BY_1;
                        *k2_div = PIXEL_RATE_DIV_BY_2;