linux-kernel - [RFC PATCH 8/9] i2c: i2c-mux: Allow for NULL select callback

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Date:	Thu, 18 Feb 2016 17:53:13 +0200
From:	Daniel Baluta <daniel.baluta@...el.com>
To:	jic23@...nel.org
Cc:	knaack.h@....de, lars@...afoo.de, pmeerw@...erw.net,
	linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
	wsa@...-dreams.de, linux-i2c@...r.kernel.org,
	lucas.demarchi@...el.com, daniel.baluta@...el.com,
	srinivas.pandruvada@...ux.intel.com, ggao@...ensense.com,
	adi.reus@...il.com, cmo@...exis.com, mwelling@...e.org
Subject: [RFC PATCH 8/9] i2c: i2c-mux: Allow for NULL select callback

From: Adriana Reus <adriana.reus@...el.com>

Add a check in i2c_mux_master_xfer before calling the select callback.
This is necessary so that NULL callbacks can be safely registered.

Signed-off-by: Adriana Reus <adriana.reus@...el.com>
Signed-off-by: Daniel Baluta <daniel.baluta@...el.com>
---
 drivers/i2c/i2c-mux.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c
index 00fc5b1..74d1700 100644
--- a/drivers/i2c/i2c-mux.c
+++ b/drivers/i2c/i2c-mux.c
@@ -46,11 +46,12 @@ static int i2c_mux_master_xfer(struct i2c_adapter *adap,
 {
 	struct i2c_mux_priv *priv = adap->algo_data;
 	struct i2c_adapter *parent = priv->parent;
-	int ret;
+	int ret = 0;
 
 	/* Switch to the right mux port and perform the transfer. */
 
-	ret = priv->select(parent, priv->mux_priv, priv->chan_id);
+	if (priv->select)
+		ret = priv->select(parent, priv->mux_priv, priv->chan_id);
 	if (ret >= 0)
 		ret = __i2c_transfer(parent, msgs, num);
 	if (priv->deselect)
@@ -66,11 +67,12 @@ static int i2c_mux_smbus_xfer(struct i2c_adapter *adap,
 {
 	struct i2c_mux_priv *priv = adap->algo_data;
 	struct i2c_adapter *parent = priv->parent;
-	int ret;
+	int ret = 0;
 
 	/* Select the right mux port and perform the transfer. */
 
-	ret = priv->select(parent, priv->mux_priv, priv->chan_id);
+	if (priv->select)
+		ret = priv->select(parent, priv->mux_priv, priv->chan_id);
 	if (ret >= 0)
 		ret = parent->algo->smbus_xfer(parent, addr, flags,
 					read_write, command, size, data);
-- 
2.5.0