linux-kernel - [PATCH 4.4 21/31] drm: adv7511: really enable interrupts for EDID detection

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Date:   Tue, 12 Sep 2017 09:56:16 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Archit Taneja <architt@...eaurora.org>,
        Thong Ho <thong.ho.px@....renesas.com>,
        Nhan Nguyen <nhan.nguyen.yb@...esas.com>
Subject: [PATCH 4.4 21/31] drm: adv7511: really enable interrupts for EDID detection

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Wolfram Sang <wsa+renesas@...g-engineering.com>

commit d0be8584b01160eb6f49e77f8e9c1da286bb4ffb upstream.

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@...g-engineering.com>
Tested-by: Archit Taneja <architt@...eaurora.org>
Signed-off-by: Thong Ho <thong.ho.px@....renesas.com>
Signed-off-by: Nhan Nguyen <nhan.nguyen.yb@...esas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/gpu/drm/i2c/adv7511.c |   25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

--- a/drivers/gpu/drm/i2c/adv7511.c
+++ b/drivers/gpu/drm/i2c/adv7511.c
@@ -362,12 +362,19 @@ static void adv7511_power_on(struct adv7
 {
 	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_
 
 	/* 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;
 	}