drm/amd/display: treat memory as a single-channel for asymmetric memory v2

Previous change had been reverted since it caused hang.
Remake change to avoid defect.

[Why]
1. Driver use umachannelnumber to calculate watermarks for stutter.
In asymmetric memory config, the actual bandwidth is less than
dual-channel. The bandwidth should be the same as single-channel.
2. We found single rank dimm need additional delay time for stutter.

[How]
Get information from each DIMM. Treat memory config as a single-channel
for asymmetric memory in bandwidth calculating.
Add additional delay time for single rank dimm.

Fixes: b8720ed ("drm/amd/display: System black screen hangs on driver load")
Signed-off-by: Hugo Hu <[email protected]>
Reviewed-by: Sung Lee <[email protected]>
Acked-by: Aurabindo Pillai <[email protected]>
Tested-by: Daniel Wheeler <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

Author: Hugo Hu

drivers/gpu/drm/amd/display/dc/clk_mgr/dcn21/rn_clk_mgr.c

@@ -769,6 +769,43 @@ static struct wm_table ddr4_wm_table_rn = {
 	}
 };
 
+static struct wm_table ddr4_1R_wm_table_rn = {
+	.entries = {
+		{
+			.wm_inst = WM_A,
+			.wm_type = WM_TYPE_PSTATE_CHG,
+			.pstate_latency_us = 11.72,
+			.sr_exit_time_us = 13.90,
+			.sr_enter_plus_exit_time_us = 14.80,
+			.valid = true,
+		},
+		{
+			.wm_inst = WM_B,
+			.wm_type = WM_TYPE_PSTATE_CHG,
+			.pstate_latency_us = 11.72,
+			.sr_exit_time_us = 13.90,
+			.sr_enter_plus_exit_time_us = 14.80,
+			.valid = true,
+		},
+		{
+			.wm_inst = WM_C,
+			.wm_type = WM_TYPE_PSTATE_CHG,
+			.pstate_latency_us = 11.72,
+			.sr_exit_time_us = 13.90,
+			.sr_enter_plus_exit_time_us = 14.80,
+			.valid = true,
+		},
+		{
+			.wm_inst = WM_D,
+			.wm_type = WM_TYPE_PSTATE_CHG,
+			.pstate_latency_us = 11.72,
+			.sr_exit_time_us = 13.90,
+			.sr_enter_plus_exit_time_us = 14.80,
+			.valid = true,
+		},
+	}
+};
+
 static struct wm_table lpddr4_wm_table_rn = {
 	.entries = {
 		{
@@ -953,8 +990,12 @@ void rn_clk_mgr_construct(
 		} else {
 			if (is_green_sardine)
 				rn_bw_params.wm_table = ddr4_wm_table_gs;
-			else
-				rn_bw_params.wm_table = ddr4_wm_table_rn;
+			else {
+				if (ctx->dc->config.is_single_rank_dimm)
+					rn_bw_params.wm_table = ddr4_1R_wm_table_rn;
+				else
+					rn_bw_params.wm_table = ddr4_wm_table_rn;
+			}
 		}
 		/* Saved clocks configured at boot for debug purposes */
 		rn_dump_clk_registers(&clk_mgr->base.boot_snapshot, &clk_mgr->base, &log_info);
@@ -972,6 +1013,9 @@ void rn_clk_mgr_construct(
 		if (status == PP_SMU_RESULT_OK &&
 		    ctx->dc_bios && ctx->dc_bios->integrated_info) {
 			rn_clk_mgr_helper_populate_bw_params (clk_mgr->base.bw_params, &clock_table, ctx->dc_bios->integrated_info);
+			/* treat memory config as single channel if memory is asymmetrics. */
+			if (ctx->dc->config.is_asymmetric_memory)
+				clk_mgr->base.bw_params->num_channels = 1;
 		}
 	}
 

drivers/gpu/drm/amd/display/dc/dc.h

@@ -308,6 +308,8 @@ struct dc_config {
 #endif
 	uint64_t vblank_alignment_dto_params;
 	uint8_t  vblank_alignment_max_frame_time_diff;
+	bool is_asymmetric_memory;
+	bool is_single_rank_dimm;
 };
 
 enum visual_confirm {