plugins: adrv9002: constrain RSSI reads

With the changes in the device driver API, reading the RSSI on a channel
that's not enabled will trow an error. Hence, instead of flooding the
device with error's (and the kernel log), don't read the RSSI for
channels that are not enabled.

With the above, as we always need to read the ensm widget, make use
iio_widget_update_value() to update it in case port enable is set to pin
(and hence avoiding another call into the device).

Signed-off-by: Nuno Sa <nuno.sa@analog.com>
(cherry picked from commit 54efaad)

plugins/adrv9002.c

@@ -489,7 +489,7 @@ static void update_label(const struct adrv9002_gtklabel *label)
 	gtk_label_set_text(label->labels, attr_val);
 }
 
-static void update_special_widgets(struct adrv9002_common *chann)
+static void update_special_widgets(struct adrv9002_common *chann, const char *ensm, size_t len)
 {
 	char *gain_ctl = gtk_combo_box_text_get_active_text(
 		GTK_COMBO_BOX_TEXT(chann->gain_ctrl.widget));
@@ -499,8 +499,8 @@ static void update_special_widgets(struct adrv9002_common *chann)
 	if (gain_ctl && strcmp(gain_ctl, "spi"))
 		iio_widget_update_block_signals_by_data(&chann->gain);
 
-	if (port_en && strcmp(port_en, "spi"))
-		iio_widget_update_block_signals_by_data(&chann->ensm);
+	if (port_en && strcmp(port_en, "spi") && ensm)
+		iio_widget_update_value(&chann->ensm, ensm, len);
 
 	g_free(gain_ctl);
 	g_free(port_en);
@@ -513,13 +513,25 @@ static void update_special_rx_widgets(struct adrv9002_rx *rx, const int n_widget
 	for (i = 0; i < n_widgets; i++) {
 		char *digital_gain = gtk_combo_box_text_get_active_text(
 			GTK_COMBO_BOX_TEXT(rx[i].digital_gain_ctl.widget));
+		char ensm[32] = {0};
 
 		if (!rx[i].rx.enabled)
 			goto nex_widget;
 
-		update_label(&rx[i].rssi);
+		/*
+		 * There was a change in the driver API where an error is returned if we try to read
+		 * the RSSI level if the channel is not enabled. Hence, make sure we only update it
+		 * if the channel is enabled.
+		 */
+		if (iio_channel_attr_read(rx[i].rx.ensm.chn, rx[i].rx.ensm.attr_name, ensm,
+					  sizeof(ensm)) > 0 && !strcmp(ensm, "rf_enabled"))
+			update_label(&rx[i].rssi);
 		update_label(&rx[i].decimated_power);
-		update_special_widgets(&rx[i].rx);
+		/*
+		 * Pass in ensm as we already got it and so no need for another possible
+		 * remote call into the device.
+		 */
+		update_special_widgets(&rx[i].rx, ensm, sizeof(ensm));
 
 		if (digital_gain && strstr(digital_gain, "automatic"))
 			iio_widget_update_block_signals_by_data(&rx[i].intf_gain);
@@ -536,7 +548,7 @@ static void update_special_tx_widgets(struct adrv9002_common *tx, const int n_wi
 		if (!tx[i].enabled)
 			continue;
 
-		update_special_widgets(&tx[i]);
+		update_special_widgets(&tx[i], NULL, 0);
 	}
 }