[PATCH 3/5] drm/amd/display: Fix Vega10 black screen after mode change

[Bhawanpreet.Lakha@xxxxxxx (Bhawanpreet Lakha)]

From: "Jerry (Fangzhi) Zuo" <Jerry.Zuo@xxxxxxx>

[Why]
The sequence is slightly changed when bring .set_bandwidth out
from the end of programming backend to the end of programming
surface. Vega10 doesn't like to get clocks updated if
stream_count is zero in the current context (Atomic Reset).

[How]
Do not update clocks if no stream is showing up in the context.

Fixes 1b2b130192 "dc: Remove 300Mhz minimum disp clk limit."

Change-Id: Icd5694f834d4c8a5e16a950059961aff232f8a46
Signed-off-by: Jerry (Fangzhi) Zuo <Jerry.Zuo at amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng at amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha at amd.com>
---
 drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c |  2 +-
 drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.h |  5 +++++
 drivers/gpu/drm/amd/display/dc/dce120/dce120_hw_sequencer.c | 10 ++++++++++
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c b/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
index e0444497cbf9..775a527de4f3 100644
--- a/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
+++ b/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
@@ -2534,7 +2534,7 @@ static void pplib_apply_display_requirements(
 	dc->prev_display_config = *pp_display_cfg;
 }
 
-static void dce110_set_bandwidth(
+void dce110_set_bandwidth(
 		struct dc *dc,
 		struct dc_state *context,
 		bool decrease_allowed)
diff --git a/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.h b/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.h
index d6db3dbd9015..e4c5db75c4c6 100644
--- a/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.h
+++ b/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.h
@@ -68,6 +68,11 @@ void dce110_fill_display_configs(
 	const struct dc_state *context,
 	struct dm_pp_display_configuration *pp_display_cfg);
 
+void dce110_set_bandwidth(
+		struct dc *dc,
+		struct dc_state *context,
+		bool decrease_allowed);
+
 uint32_t dce110_get_min_vblank_time_us(const struct dc_state *context);
 
 void dp_receiver_power_ctrl(struct dc_link *link, bool on);
diff --git a/drivers/gpu/drm/amd/display/dc/dce120/dce120_hw_sequencer.c b/drivers/gpu/drm/amd/display/dc/dce120/dce120_hw_sequencer.c
index e96ff86d2fc3..5853522a6182 100644
--- a/drivers/gpu/drm/amd/display/dc/dce120/dce120_hw_sequencer.c
+++ b/drivers/gpu/drm/amd/display/dc/dce120/dce120_hw_sequencer.c
@@ -244,7 +244,16 @@ static void dce120_update_dchub(
 	dh_data->dchub_info_valid = false;
 }
 
+static void dce120_set_bandwidth(
+		struct dc *dc,
+		struct dc_state *context,
+		bool decrease_allowed)
+{
+	if (context->stream_count <= 0)
+		return;
 
+	dce110_set_bandwidth(dc, context, decrease_allowed);
+}
 
 void dce120_hw_sequencer_construct(struct dc *dc)
 {
@@ -254,5 +263,6 @@ void dce120_hw_sequencer_construct(struct dc *dc)
 	dce110_hw_sequencer_construct(dc);
 	dc->hwss.enable_display_power_gating = dce120_enable_display_power_gating;
 	dc->hwss.update_dchub = dce120_update_dchub;
+	dc->hwss.set_bandwidth = dce120_set_bandwidth;
 }
 
-- 
2.14.1