drm/amd/display: Set i2c memory to light sleep during hw init

[WHY]
i2c memory doesn't get set to light sleep on hw init as intended

[HOW]
Set i2c to light sleep after reg gets zeroed, ensuring memory power
control doesn't get disabled for any other DIO memory
Reviewed-by: Haonan Wang <Haonan.Wang2@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Acked-by: Agustin Gutierrez <agustin.gutierrez@amd.com>
Signed-off-by: Michael Strauss <michael.strauss@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -1151,7 +1151,8 @@ struct dce_hwseq_registers {
 	type DOMAIN_POWER_GATE;\
 	type DOMAIN_PGFSM_PWR_STATUS;\
 	type HPO_HDMISTREAMCLK_G_GATE_DIS;\
-	type DISABLE_HOSTVM_FORCE_ALLOW_PSTATE;
+	type DISABLE_HOSTVM_FORCE_ALLOW_PSTATE;\
+	type I2C_LIGHT_SLEEP_FORCE;
 
 struct dce_hwseq_shift {
 	HWSEQ_REG_FIELD_LIST(uint8_t)

drivers/gpu/drm/amd/display/dc/dcn31/dcn31_hwseq.c

@@ -50,6 +50,7 @@
 #include "dcn10/dcn10_hw_sequencer.h"
 #include "inc/link_enc_cfg.h"
 #include "dcn30/dcn30_vpg.h"
+#include "dce/dce_i2c_hw.h"
 
 #define DC_LOGGER_INIT(logger)
 
@@ -259,6 +260,10 @@ void dcn31_init_hw(struct dc *dc)
 	/* power AFMT HDMI memory TODO: may move to dis/en output save power*/
 	REG_WRITE(DIO_MEM_PWR_CTRL, 0);
 
+	// Set i2c to light sleep until engine is setup
+	if (dc->debug.enable_mem_low_power.bits.i2c)
+		REG_UPDATE(DIO_MEM_PWR_CTRL, I2C_LIGHT_SLEEP_FORCE, 1);
+
 	if (!dc->debug.disable_clock_gate) {
 		/* enable all DCN clock gating */
 		REG_WRITE(DCCG_GATE_DISABLE_CNTL, 0);

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

@@ -899,7 +899,8 @@ static const struct dce_hwseq_registers hwseq_reg = {
 	HWS_SF(, DMU_MEM_PWR_CNTL, DMCU_ERAM_MEM_PWR_FORCE, 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(, MMHUBBUB_MEM_PWR_CNTL, VGA_MEM_PWR_FORCE, mask_sh)
+	HWS_SF(, MMHUBBUB_MEM_PWR_CNTL, VGA_MEM_PWR_FORCE, mask_sh), \
+	HWS_SF(, DIO_MEM_PWR_CTRL, I2C_LIGHT_SLEEP_FORCE, mask_sh)
 
 static const struct dce_hwseq_shift hwseq_shift = {
 		HWSEQ_DCN31_MASK_SH_LIST(__SHIFT)