power: supply: bq25890: Fix setting of F_CONV_RATE rate when disabling HiZ mode

The recent "power: supply: bq25890: Add HiZ mode support" change
leaves F_CONV_RATE rate unset when disabling HiZ mode (setting
POWER_SUPPLY_PROP_ONLINE to 1) while a charger is connected.

Separate the resetting HiZ mode (when necessary because of a charger
(re)plug event) into its own "if {}" block which runs first.

And fix the setting of F_CONV_RATE rate by adding helper variables for
the old and new F_CONV_RATE state which check both the online and hiz bits
and then compare the helper variables to see if a F_CONV_RATE update is
necessary.
Reviewed-by: Marek Vasut <marex@denx.de>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/bq25890_charger.c

@@ -795,6 +795,7 @@ static int bq25890_get_chip_state(struct bq25890_device *bq,
 
 static irqreturn_t __bq25890_handle_irq(struct bq25890_device *bq)
 {
+	bool adc_conv_rate, new_adc_conv_rate;
 	struct bq25890_state new_state;
 	int ret;
 
@@ -805,34 +806,26 @@ static irqreturn_t __bq25890_handle_irq(struct bq25890_device *bq)
 	if (!memcmp(&bq->state, &new_state, sizeof(new_state)))
 		return IRQ_NONE;
 
-	/* power removed or HiZ */
-	if ((!new_state.online || new_state.hiz) && bq->state.online) {
-		/* disable ADC */
-		ret = bq25890_field_write(bq, F_CONV_RATE, 0);
-		if (ret < 0)
-			goto error;
-	} else if (new_state.online && !bq->state.online) {
 	/*
-		 * Restore HiZ bit in case it was set by user.
-		 * The chip does not retain this bit once the
-		 * cable is re-plugged, hence the bit must be
-		 * reset manually here.
+	 * Restore HiZ bit in case it was set by user. The chip does not retain
+	 * this bit on cable replug, hence the bit must be reset manually here.
 	 */
-		if (bq->force_hiz) {
+	if (new_state.online && !bq->state.online && bq->force_hiz) {
 		ret = bq25890_field_write(bq, F_EN_HIZ, bq->force_hiz);
 		if (ret < 0)
 			goto error;
 		new_state.hiz = 1;
 	}
 
-		if (!new_state.hiz) {
-			/* power inserted and not HiZ */
-			/* enable ADC, to have control of charge current/voltage */
-			ret = bq25890_field_write(bq, F_CONV_RATE, 1);
+	/* Should period ADC sampling be enabled? */
+	adc_conv_rate = bq->state.online && !bq->state.hiz;
+	new_adc_conv_rate = new_state.online && !new_state.hiz;
+
+	if (new_adc_conv_rate != adc_conv_rate) {
+		ret = bq25890_field_write(bq, F_CONV_RATE, new_adc_conv_rate);
 		if (ret < 0)
 			goto error;
 	}
-	}
 
 	bq->state = new_state;
 	power_supply_changed(bq->charger);