drm/amd/display: add support for per-state dummy-pstate latency

[why]
Dummy pstate latency actually varies between different
UCLK frequencies, when calculating watermark C, if DAL
always assumes worst case, then it can lead to dummy
pstate not supported scenarios.

[how]
Rather than statically calculating dummy pstate using
worst case, we store the entire table of UCLK to dummy
pstate relationships.  On a per mode basis, we calculate
the actual UCLK lower limit, and use the dynamic worst
case dummy pstate latency.  This prevents the situation
where we don't support full p-state (which will force
high DPM), but still use low DPM dummy pstate latency.
Signed-off-by: Jun Lei <jun.lei@amd.com>
Reviewed-by: Joshua Aberback <Joshua.Aberback@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/inc/hw/clk_mgr.h

@@ -198,11 +198,17 @@ struct wm_table {
 #endif
 };
 
+struct dummy_pstate_entry {
+	unsigned int dram_speed_mts;
+	unsigned int dummy_pstate_latency_us;
+};
+
 struct clk_bw_params {
 	unsigned int vram_type;
 	unsigned int num_channels;
 	struct clk_limit_table clk_table;
 	struct wm_table wm_table;
+	struct dummy_pstate_entry dummy_pstate_table[4];
 };
 /* Public interfaces */