drm: adv7511: really enable interrupts for EDID detection

The interrupts for EDID_READY or DDC_ERROR were never enabled in this
driver, so reading EDID always timed out when chip was powered down and
interrupts were used. Fix this and also remove clearing the interrupt
flags, they are cleared in POWER_DOWN mode anyhow (unlike the interrupt
enable flags) according to docs and my tests.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Archit Taneja <architt@codeaurora.org>

drivers/gpu/drm/i2c/adv7511.c

@@ -362,12 +362,19 @@ static void adv7511_power_on(struct adv7511 *adv7511)
 {
 	adv7511->current_edid_segment = -1;
 
-	regmap_write(adv7511->regmap, ADV7511_REG_INT(0),
-		     ADV7511_INT0_EDID_READY);
-	regmap_write(adv7511->regmap, ADV7511_REG_INT(1),
-		     ADV7511_INT1_DDC_ERROR);
 	regmap_update_bits(adv7511->regmap, ADV7511_REG_POWER,
 			   ADV7511_POWER_POWER_DOWN, 0);
+	if (adv7511->i2c_main->irq) {
+		/*
+		 * Documentation says the INT_ENABLE registers are reset in
+		 * POWER_DOWN mode. My 7511w preserved the bits, however.
+		 * Still, let's be safe and stick to the documentation.
+		 */
+		regmap_write(adv7511->regmap, ADV7511_REG_INT_ENABLE(0),
+			     ADV7511_INT0_EDID_READY);
+		regmap_write(adv7511->regmap, ADV7511_REG_INT_ENABLE(1),
+			     ADV7511_INT1_DDC_ERROR);
+	}
 
 	/*
 	 * Per spec it is allowed to pulse the HDP signal to indicate that the
@@ -567,12 +574,14 @@ static int adv7511_get_modes(struct drm_encoder *encoder,
 
 	/* Reading the EDID only works if the device is powered */
 	if (!adv7511->powered) {
-		regmap_write(adv7511->regmap, ADV7511_REG_INT(0),
-			     ADV7511_INT0_EDID_READY);
-		regmap_write(adv7511->regmap, ADV7511_REG_INT(1),
-			     ADV7511_INT1_DDC_ERROR);
 		regmap_update_bits(adv7511->regmap, ADV7511_REG_POWER,
 				   ADV7511_POWER_POWER_DOWN, 0);
+		if (adv7511->i2c_main->irq) {
+			regmap_write(adv7511->regmap, ADV7511_REG_INT_ENABLE(0),
+				     ADV7511_INT0_EDID_READY);
+			regmap_write(adv7511->regmap, ADV7511_REG_INT_ENABLE(1),
+				     ADV7511_INT1_DDC_ERROR);
+		}
 		adv7511->current_edid_segment = -1;
 	}