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From: John Stultz <john.stultz@linaro.org>
Newsgroups: linux.kernel
Subject: [RFC][PATCH 5/5 v3] drm/bridge: adv7511: Reuse __adv7511_power_on/off() when probing EDID
Date: Mon, 12 Dec 2016 22:10:01 +0100
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I've found that by just turning the chip on and off via the
POWER_DOWN register, I end up getting i2c_transfer errors
on HiKey.

Investigating further, it seems some of the register state
in the regmap cache is somehow getting lost. Using the logic
in __adv7511_power_on/off() which syncs and dirtys the cache
avoids this issue.

Thus this patch changes the EDID probing logic so that we
re-use the __adv7511_power_on/off() calls.

Cc: David Airlie <airlied@linux.ie>
Cc: Archit Taneja <architt@codeaurora.org>
Cc: Wolfram Sang <wsa+renesas@sang-engineering.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
 drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 17 +++--------------
 1 file changed, 3 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
index dbdb71c..24573e0 100644
--- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
+++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
@@ -572,24 +572,13 @@ static int adv7511_get_modes(struct adv7511 *adv7511,
 	unsigned int count;
 
 	/* Reading the EDID only works if the device is powered */
-	if (!adv7511->powered) {
-		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;
-	}
+	if (!adv7511->powered)
+		__adv7511_power_on(adv7511);
 
 	edid = drm_do_get_edid(connector, adv7511_get_edid_block, adv7511);
 
 	if (!adv7511->powered)
-		regmap_update_bits(adv7511->regmap, ADV7511_REG_POWER,
-				   ADV7511_POWER_POWER_DOWN,
-				   ADV7511_POWER_POWER_DOWN);
+		__adv7511_power_off(adv7511);
 
 	kfree(adv7511->edid);
 	adv7511->edid = edid;
-- 
2.7.4