rtc: isl1208: Update correct procedure for clearing alarm

As per the latest HW manual[1], there is an internal delay(~250 microsec)
from setting ALME = 0 to disabling the alarm function, so the user must
add a short delay of greater than 250µs between setting ALME = 0 and
clearing ALM.

Currently setting of ALME = 0 is done after clearing the ALM, so just
reverse the operation and add a delay of 275 microsec.

[1]https://www.renesas.com/us/en/document/dst/raa215300-datasheet?r=1506351

Signed-off-by: Biju Das <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexandre Belloni <[email protected]>

Author: bijudas

drivers/rtc/rtc-isl1208.c

@@ -663,6 +663,13 @@ isl1208_rtc_interrupt(int irq, void *data)
 
 		rtc_update_irq(isl1208->rtc, 1, RTC_IRQF | RTC_AF);
 
+		/* Disable the alarm */
+		err = isl1208_rtc_toggle_alarm(client, 0);
+		if (err)
+			return err;
+
+		fsleep(275);
+
 		/* Clear the alarm */
 		sr &= ~ISL1208_REG_SR_ALM;
 		sr = i2c_smbus_write_byte_data(client, ISL1208_REG_SR, sr);
@@ -671,11 +678,6 @@ isl1208_rtc_interrupt(int irq, void *data)
 				__func__);
 		else
 			handled = 1;
-
-		/* Disable the alarm */
-		err = isl1208_rtc_toggle_alarm(client, 0);
-		if (err)
-			return err;
 	}
 
 	if (isl1208->config->has_tamper && (sr & ISL1208_REG_SR_EVT)) {