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core/linux-nyan/v2-i2c-of-Try-to-find-an-I2C-adapter-matching-the-parent.patch

@@ -0,0 +1,76 @@
+From patchwork Fri Jan 25 13:11:42 2019
+Content-Type: text/plain; charset="utf-8"
+MIME-Version: 1.0
+Content-Transfer-Encoding: 7bit
+Subject: [v2] i2c: of: Try to find an I2C adapter matching the parent
+X-Patchwork-Submitter: Thierry Reding <thierry.reding@gmail.com>
+X-Patchwork-Id: 1031073
+Message-Id: <20190125131142.26837-1-thierry.reding@gmail.com>
+To: Wolfram Sang <wsa@the-dreams.de>
+Cc: Rob Herring <robh+dt@kernel.org>, Lucas Stach <l.stach@pengutronix.de>,
+ Andrzej Hajda <a.hajda@samsung.com>, Vlado Plaga <rechner@vlado-do.de>,
+ Tristan Bastian <tristan-c.bastian@gmx.de>,
+ linux-i2c@vger.kernel.org, dri-devel@lists.freedesktop.org,
+ linux-tegra@vger.kernel.org
+Date: Fri, 25 Jan 2019 14:11:42 +0100
+From: Thierry Reding <thierry.reding@gmail.com>
+List-Id: <linux-i2c.vger.kernel.org>
+
+From: Thierry Reding <treding@nvidia.com>
+
+If an I2C adapter doesn't match the provided device tree node, also try
+matching the parent's device tree node. This allows finding an adapter
+based on the device node of the parent device that was used to register
+it.
+
+This fixes a regression on Tegra124-based Chromebooks (Nyan) where the
+eDP controller registers an I2C adapter that is used to read to EDID.
+After commit 993a815dcbb2 ("dt-bindings: panel: Add missing .txt
+suffix") this stopped working because the I2C adapter could no longer
+be found. The approach in this patch fixes the regression without
+introducing the issues that the above commit solved.
+
+Fixes: 17ab7806de0c ("drm: don't link DP aux i2c adapter to the hardware device node")
+Signed-off-by: Thierry Reding <treding@nvidia.com>
+Tested-by: Tristan Bastian <tristan-c.bastian@gmx.de>
+Tested-by: Tristan Bastian <tristan-c.bastian@gmx.de>
+---
+Changes in v2:
+- check for both device and parent device tree nodes for each device
+  instead of looping through the list of devices twice
+
+ drivers/i2c/i2c-core-of.c | 14 +++++++++++++-
+ 1 file changed, 13 insertions(+), 1 deletion(-)
+
+diff --git a/drivers/i2c/i2c-core-of.c b/drivers/i2c/i2c-core-of.c
+index 6cb7ad608bcd..0f01cdba9d2c 100644
+--- a/drivers/i2c/i2c-core-of.c
++++ b/drivers/i2c/i2c-core-of.c
+@@ -121,6 +121,17 @@ static int of_dev_node_match(struct device *dev, void *data)
+ 	return dev->of_node == data;
+ }
+
++static int of_dev_or_parent_node_match(struct device *dev, void *data)
++{
++	if (dev->of_node == data)
++		return 1;
++
++	if (dev->parent)
++		return dev->parent->of_node == data;
++
++	return 0;
++}
++
+ /* must call put_device() when done with returned i2c_client device */
+ struct i2c_client *of_find_i2c_device_by_node(struct device_node *node)
+ {
+@@ -145,7 +156,8 @@ struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
+ 	struct device *dev;
+ 	struct i2c_adapter *adapter;
+
+-	dev = bus_find_device(&i2c_bus_type, NULL, node, of_dev_node_match);
++	dev = bus_find_device(&i2c_bus_type, NULL, node,
++			      of_dev_or_parent_node_match);
+ 	if (!dev)
+ 		return NULL;
+