mmi_parallel_charger_iio:optimize the pdo select

optimize the pdo select when vbus request is reduced

Change-Id: I8fc6921014561ff107981ac623915d6f44a01f58
Reviewed-on: https://gerrit.mot.com/2673991
SME-Granted: SME Approvals Granted
SLTApproved: Slta Waiver
Tested-by: Jira Key
Reviewed-by: Lei Chen <chenl18@motorola.com>
Reviewed-by: Xiangpo Zhao <zhaoxp3@motorola.com>
Submit-Approved: Jira Key

drivers/power/mmi_parallel_charger_iio/mmi_charger_pump_policy.c

@@ -43,6 +43,8 @@
 #include <linux/types.h>
 #include "mmi_charger_core.h"
 
+#define MINIMUM_CHARGER_VOLT			5100000
+
 typedef enum  {
 	PM_STATE_DISCONNECT,
 	PM_STATE_ENTRY,
@@ -1154,7 +1156,7 @@ void mmi_chrg_sm_work_func(struct work_struct *work)
 		chip->pd_request_curr = TYPEC_HIGH_CURRENT_UA;
 		mmi_chrg_info(chip,"ibatt : %dmA, step cc curr : %dmA\n",
 						ibatt_curr, chrg_step->chrg_step_cc_curr);
-		if (ibatt_curr > chrg_step->chrg_step_cc_curr) {
+		if ((ibatt_curr > chrg_step->chrg_step_cc_curr) && (chip->pd_request_volt > MINIMUM_CHARGER_VOLT)) {
 			chip->pd_request_volt -= CV_DELTA_VOLT;
 
 			mmi_chrg_dbg(chip, PR_MOTO, "Reduce pps volt %dmV, curr %dmA\n ",