[PATCH 35/35] drm/amd/display: limit display clock to 100MHz to avoid FIFO error

[Rodrigo Siqueira]

From: Yu-ting Shen <Yu-ting.Shen at amd.com>

[Why]
when changing display clock, SMU need to use power up DFS and use
DENTIST to ramp DFS DID to switch target frequency before switching back
to bypass.

[How]
fixed the minimum display clock to 100MHz, it's W/A the same with PCO.

Signed-off-by: Yu-ting Shen <Yu-ting.Shen at amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng at amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira at amd.com>
Acked-by: Harry Wentland <harry.wentland at amd.com>
---
 drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c | 3 +++
 drivers/gpu/drm/amd/display/dc/dcn21/dcn21_resource.c | 1 +
 2 files changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c
index 883ecd2ed4c8..78971b6b195c 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c
@@ -2786,6 +2786,9 @@ void dcn20_calculate_dlg_params(
 							!= dm_dram_clock_change_unsupported;
 	context->bw_ctx.bw.dcn.clk.dppclk_khz = 0;
 
+	if (context->bw_ctx.bw.dcn.clk.dispclk_khz < dc->debug.min_disp_clk_khz)
+		context->bw_ctx.bw.dcn.clk.dispclk_khz = dc->debug.min_disp_clk_khz;
+
 	/*
 	 * An artifact of dml pipe split/odm is that pipes get merged back together for
 	 * calculation. Therefore we need to only extract for first pipe in ascending index order
diff --git a/drivers/gpu/drm/amd/display/dc/dcn21/dcn21_resource.c b/drivers/gpu/drm/amd/display/dc/dcn21/dcn21_resource.c
index aa73025c1747..dce4966eca20 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn21/dcn21_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn21/dcn21_resource.c
@@ -859,6 +859,7 @@ static const struct dc_debug_options debug_defaults_drv = {
 		.timing_trace = false,
 		.clock_trace = true,
 		.disable_pplib_clock_request = true,
+		.min_disp_clk_khz = 100000,
 		.pipe_split_policy = MPC_SPLIT_AVOID_MULT_DISP,
 		.force_single_disp_pipe_split = false,
 		.disable_dcc = DCC_ENABLE,
-- 
2.25.0