drm/amd/display: Set min dcfclk if pipe count is 0

[WHY]
Clocks don't get recalculated in 0 stream/0 pipe configs,
blocking S0i3 if dcfclk gets high enough

[HOW]
Create DCN31 copy of DCN30 bandwidth validation func which
doesn't entirely skip validation in 0 pipe scenarios

Override dcfclk to vlevel 0/min value during validation if pipe
count is 0

Reviewed-by: Eric Yang <[e-mail]>
Acked-by: Qingqing Zhuo <[e-mail]>
Signed-off-by: Michael Strauss <[e-mail]>
Tested-by: Daniel Wheeler <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/display/dc/dcn30/dcn30_resource.c

···
 	return pipe;
 }
 
-static noinline bool dcn30_internal_validate_bw(
+noinline bool dcn30_internal_validate_bw(
 		struct dc *dc,
 		struct dc_state *context,
 		display_e2e_pipe_params_st *pipes,

drivers/gpu/drm/amd/display/dc/dcn30/dcn30_resource.h

···
 
 bool dcn30_validate_bandwidth(struct dc *dc, struct dc_state *context,
 		bool fast_validate);
+bool dcn30_internal_validate_bw(
+		struct dc *dc,
+		struct dc_state *context,
+		display_e2e_pipe_params_st *pipes,
+		int *pipe_cnt_out,
+		int *vlevel_out,
+		bool fast_validate);
 void dcn30_calculate_wm_and_dlg(
 		struct dc *dc, struct dc_state *context,
 		display_e2e_pipe_params_st *pipes,

drivers/gpu/drm/amd/display/dc/dcn31/dcn31_resource.c

···
 	if (context->bw_ctx.dml.soc.min_dcfclk > dcfclk)
 		dcfclk = context->bw_ctx.dml.soc.min_dcfclk;
 
+	/* We don't recalculate clocks for 0 pipe configs, which can block
+	 * S0i3 as high clocks will block low power states
+	 * Override any clocks that can block S0i3 to min here
+	 */
+	if (pipe_cnt == 0) {
+		context->bw_ctx.bw.dcn.clk.dcfclk_khz = dcfclk; // always should be vlevel 0
+		return;
+	}
+
 	pipes[0].clks_cfg.voltage = vlevel;
 	pipes[0].clks_cfg.dcfclk_mhz = dcfclk;
 	pipes[0].clks_cfg.socclk_mhz = context->bw_ctx.dml.soc.clock_limits[vlevel].socclk_mhz;
···
 	DC_FP_END();
 }
 
+bool dcn31_validate_bandwidth(struct dc *dc,
+		struct dc_state *context,
+		bool fast_validate)
+{
+	bool out = false;
+
+	BW_VAL_TRACE_SETUP();
+
+	int vlevel = 0;
+	int pipe_cnt = 0;
+	display_e2e_pipe_params_st *pipes = kzalloc(dc->res_pool->pipe_count * sizeof(display_e2e_pipe_params_st), GFP_KERNEL);
+	DC_LOGGER_INIT(dc->ctx->logger);
+
+	BW_VAL_TRACE_COUNT();
+
+	out = dcn30_internal_validate_bw(dc, context, pipes, &pipe_cnt, &vlevel, fast_validate);
+
+	// Disable fast_validate to set min dcfclk in alculate_wm_and_dlg
+	if (pipe_cnt == 0)
+		fast_validate = false;
+
+	if (!out)
+		goto validate_fail;
+
+	BW_VAL_TRACE_END_VOLTAGE_LEVEL();
+
+	if (fast_validate) {
+		BW_VAL_TRACE_SKIP(fast);
+		goto validate_out;
+	}
+
+	dc->res_pool->funcs->calculate_wm_and_dlg(dc, context, pipes, pipe_cnt, vlevel);
+
+	BW_VAL_TRACE_END_WATERMARKS();
+
+	goto validate_out;
+
+validate_fail:
+	DC_LOG_WARNING("Mode Validation Warning: %s failed alidation.\n",
+		dml_get_status_message(context->bw_ctx.dml.vba.ValidationStatus[context->bw_ctx.dml.vba.soc.num_states]));
+
+	BW_VAL_TRACE_SKIP(fail);
+	out = false;
+
+validate_out:
+	kfree(pipes);
+
+	BW_VAL_TRACE_FINISH();
+
+	return out;
+}
+
 static struct dc_cap_funcs cap_funcs = {
 	.get_dcc_compression_cap = dcn20_get_dcc_compression_cap
 };
···
 	.link_encs_assign = link_enc_cfg_link_encs_assign,
 	.link_enc_unassign = link_enc_cfg_link_enc_unassign,
 	.panel_cntl_create = dcn31_panel_cntl_create,
-	.validate_bandwidth = dcn30_validate_bandwidth,
+	.validate_bandwidth = dcn31_validate_bandwidth,
 	.calculate_wm_and_dlg = dcn31_calculate_wm_and_dlg,
 	.update_soc_for_wm_a = dcn31_update_soc_for_wm_a,
 	.populate_dml_pipes = dcn31_populate_dml_pipes_from_context,