drm/amd/display: Add DMCU memory low power support

[Why]
On some platforms, DMCU is no longer used. In these cases, some DMCU
memory should be completely powered off to save power.

[How]
1. Set DMCU_ERAM_MEM_PWR_FORCE to shutdown memory when DMCU is not in
   use
2. Added a debug option to allow this behaviour to be turned off
3. Set all memory low power debug options to off first, to not
   immediately cause problems
Signed-off-by: Jacky Liao <ziyu.liao@amd.com>
Reviewed-by: Eric Yang <eric.yang2@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -420,6 +420,8 @@ struct dc_bw_validation_profile {
 union mem_low_power_enable_options {
 	struct {
 		bool i2c: 1;
+		bool dmcu: 1;
+		bool cm: 1;
 		bool mpc: 1;
 		bool optc: 1;
 	} bits;

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

@@ -597,6 +597,7 @@ struct dce_hwseq_registers {
 	uint32_t AZALIA_CONTROLLER_CLOCK_GATING;
 	uint32_t HPO_TOP_CLOCK_CONTROL;
 	uint32_t ODM_MEM_PWR_CTRL3;
+	uint32_t DMU_MEM_PWR_CNTL;
 };
  /* set field name */
 #define HWS_SF(blk_name, reg_name, field_name, post_fix)\
@@ -836,7 +837,8 @@ struct dce_hwseq_registers {
 	HWSEQ_DCN2_MASK_SH_LIST(mask_sh), \
 	HWS_SF(, AZALIA_AUDIO_DTO, AZALIA_AUDIO_DTO_MODULE, mask_sh), \
 	HWS_SF(, ODM_MEM_PWR_CTRL3, ODM_MEM_UNASSIGNED_PWR_MODE, mask_sh), \
-	HWS_SF(, ODM_MEM_PWR_CTRL3, ODM_MEM_VBLANK_PWR_MODE, mask_sh)
+	HWS_SF(, ODM_MEM_PWR_CTRL3, ODM_MEM_VBLANK_PWR_MODE, mask_sh), \
+	HWS_SF(, DMU_MEM_PWR_CNTL, DMCU_ERAM_MEM_PWR_FORCE, mask_sh)
 
 #define HWSEQ_DCN301_MASK_SH_LIST(mask_sh)\
 	HWSEQ_DCN_MASK_SH_LIST(mask_sh), \
@@ -1046,7 +1048,8 @@ struct dce_hwseq_registers {
 	type D4VGA_MODE_ENABLE; \
 	type AZALIA_AUDIO_DTO_MODULE; \
 	type ODM_MEM_UNASSIGNED_PWR_MODE; \
-	type ODM_MEM_VBLANK_PWR_MODE;
+	type ODM_MEM_VBLANK_PWR_MODE; \
+	type DMCU_ERAM_MEM_PWR_FORCE;
 
 #define HWSEQ_DCN3_REG_FIELD_LIST(type) \
 	type HPO_HDMISTREAMCLK_GATE_DIS;

drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c

@@ -462,6 +462,13 @@ void dcn30_init_hw(struct dc *dc)
 		hws->funcs.disable_vga(dc->hwseq);
 	}
 
+	if (dc->debug.enable_mem_low_power.bits.dmcu) {
+		// Force ERAM to shutdown if DMCU is not enabled
+		if (dc->debug.disable_dmcu || dc->config.disable_dmcu) {
+			REG_UPDATE(DMU_MEM_PWR_CNTL, DMCU_ERAM_MEM_PWR_FORCE, 3);
+		}
+	}
+
 	// Set default OPTC memory power states
 	if (dc->debug.enable_mem_low_power.bits.optc) {
 		// Shutdown when unassigned and light sleep in VBLANK