drm/amdgpu/display: handle multiple numbers of fclks in dcn_calcs.c (v2)

We might get different numbers of clocks from powerplay depending
on what the OEM has populated.

v2: add assert for at least one level

Bug: https://gitlab.freedesktop.org/drm/amd/issues/963Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/calcs/dcn_calcs.c

@@ -1435,6 +1435,7 @@ void dcn_bw_update_from_pplib(struct dc *dc)
 	struct dc_context *ctx = dc->ctx;
 	struct dm_pp_clock_levels_with_voltage fclks = {0}, dcfclks = {0};
 	bool res;
+	unsigned vmin0p65_idx, vmid0p72_idx, vnom0p8_idx, vmax0p9_idx;
 
 	/* TODO: This is not the proper way to obtain fabric_and_dram_bandwidth, should be min(fclk, memclk) */
 	res = dm_pp_get_clock_levels_by_type_with_voltage(
@@ -1446,17 +1447,28 @@ void dcn_bw_update_from_pplib(struct dc *dc)
 		res = verify_clock_values(&fclks);
 
 	if (res) {
-		ASSERT(fclks.num_levels >= 3);
-		dc->dcn_soc->fabric_and_dram_bandwidth_vmin0p65 = 32 * (fclks.data[0].clocks_in_khz / 1000.0) / 1000.0;
-		dc->dcn_soc->fabric_and_dram_bandwidth_vmid0p72 = dc->dcn_soc->number_of_channels *
-				(fclks.data[fclks.num_levels - (fclks.num_levels > 2 ? 3 : 2)].clocks_in_khz / 1000.0)
-				* ddr4_dram_factor_single_Channel / 1000.0;
-		dc->dcn_soc->fabric_and_dram_bandwidth_vnom0p8 = dc->dcn_soc->number_of_channels *
-				(fclks.data[fclks.num_levels - 2].clocks_in_khz / 1000.0)
-				* ddr4_dram_factor_single_Channel / 1000.0;
-		dc->dcn_soc->fabric_and_dram_bandwidth_vmax0p9 = dc->dcn_soc->number_of_channels *
-				(fclks.data[fclks.num_levels - 1].clocks_in_khz / 1000.0)
-				* ddr4_dram_factor_single_Channel / 1000.0;
+		ASSERT(fclks.num_levels);
+
+		vmin0p65_idx = 0;
+		vmid0p72_idx = fclks.num_levels -
+			(fclks.num_levels > 2 ? 3 : (fclks.num_levels > 1 ? 2 : 1));
+		vnom0p8_idx = fclks.num_levels - (fclks.num_levels > 1 ? 2 : 1);
+		vmax0p9_idx = fclks.num_levels - 1;
+
+		dc->dcn_soc->fabric_and_dram_bandwidth_vmin0p65 =
+			32 * (fclks.data[vmin0p65_idx].clocks_in_khz / 1000.0) / 1000.0;
+		dc->dcn_soc->fabric_and_dram_bandwidth_vmid0p72 =
+			dc->dcn_soc->number_of_channels *
+			(fclks.data[vmid0p72_idx].clocks_in_khz / 1000.0)
+			* ddr4_dram_factor_single_Channel / 1000.0;
+		dc->dcn_soc->fabric_and_dram_bandwidth_vnom0p8 =
+			dc->dcn_soc->number_of_channels *
+			(fclks.data[vnom0p8_idx].clocks_in_khz / 1000.0)
+			* ddr4_dram_factor_single_Channel / 1000.0;
+		dc->dcn_soc->fabric_and_dram_bandwidth_vmax0p9 =
+			dc->dcn_soc->number_of_channels *
+			(fclks.data[vmax0p9_idx].clocks_in_khz / 1000.0)
+			* ddr4_dram_factor_single_Channel / 1000.0;
 	} else
 		BREAK_TO_DEBUGGER();