Patch "drm/bridge: adv7511: Re-write the i2c address before EDID probing" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

drm/bridge: adv7511: Re-write the i2c address before EDID probing

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
drm-bridge-adv7511-re-write-the-i2c-address-before-edid-probing.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: John Stultz <[email protected]>
Date: Mon, 16 Jan 2017 16:52:52 -0800
Subject: drm/bridge: adv7511: Re-write the i2c address before EDID probing

From: John Stultz <[email protected]>

commit 3587c856675c45809010c2cee5b21096f6e8e938 upstream.

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 turns out that some of the register state in hardware is getting lost, as the device registers are reset when the chip is powered down.

Thus this patch simply re-writes the i2c address to the ADV7511_REG_EDID_I2C_ADDR register to ensure its properly set before we try to read the EDID data.

---
 drivers/gpu/drm/i2c/adv7511.c |   11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

@@ -51,6 +51,10 @@ struct adv7511 {
 	struct gpio_desc *gpio_pd;
 };
 
+static const int edid_i2c_addr = 0x7e;
+static const int packet_i2c_addr = 0x70;
+static const int cec_i2c_addr = 0x78;
+
 static struct adv7511 *encoder_to_adv7511(struct drm_encoder *encoder)
 {
 	return to_encoder_slave(encoder)->slave_priv;

@@ -606,6 +610,9 @@ static int adv7511_get_modes(struct drm_
 				     ADV7511_INT1_DDC_ERROR);
 		}
 		adv7511->current_edid_segment = -1;
+		/* Reset the EDID_I2C_ADDR register as it might be cleared */
+		regmap_write(adv7511->regmap, ADV7511_REG_EDID_I2C_ADDR,
+				edid_i2c_addr);
 	}
 
 	edid = drm_do_get_edid(connector, adv7511_get_edid_block, adv7511);

@@ -881,10 +888,6 @@ static int adv7511_parse_dt(struct devic
 	return 0;
 }
 
-static const int edid_i2c_addr = 0x7e;
-static const int packet_i2c_addr = 0x70;
-static const int cec_i2c_addr = 0x78;
-
 static int adv7511_probe(struct i2c_client *i2c, const struct i2c_device_id *id)
 {
 	struct adv7511_link_config link_config;

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/drm-bridge-adv7511-use-work_struct-to-defer-hotplug-handing-to-out-of-irq-context.patch queue-4.4/drm-bridge-adv7511-re-write-the-i2c-address-before-edid-probing.patch queue-4.4/drm-bridge-adv7511-switch-to-using-drm_kms_helper_hotplug_event.patch