diff mbox

[RFC,8/9] i2c: i2c-mux: Allow for NULL select callback

Message ID 1455810794-3188-9-git-send-email-daniel.baluta@intel.com
State Rejected
Headers show

Commit Message

Daniel Baluta Feb. 18, 2016, 3:53 p.m. UTC 
From: Adriana Reus <adriana.reus@intel.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@intel.com>
Signed-off-by: Daniel Baluta <daniel.baluta@intel.com>
---
 drivers/i2c/i2c-mux.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

Comments

Wolfram Sang March 1, 2016, 8:30 p.m. UTC | #1 
On Thu, Feb 18, 2016 at 05:53:13PM +0200, Daniel Baluta wrote:
> From: Adriana Reus <adriana.reus@intel.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@intel.com>
> Signed-off-by: Daniel Baluta <daniel.baluta@intel.com>

Hmm, rather than supporting that in the core, I'd prefer to have the
driver pass an empty function instead. Then, in the driver, we can have
a comment explaining the special situation.
Daniel Baluta March 1, 2016, 8:38 p.m. UTC | #2 
On Tue, Mar 1, 2016 at 10:30 PM, Wolfram Sang <wsa@the-dreams.de> wrote:
> On Thu, Feb 18, 2016 at 05:53:13PM +0200, Daniel Baluta wrote:
>> From: Adriana Reus <adriana.reus@intel.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@intel.com>
>> Signed-off-by: Daniel Baluta <daniel.baluta@intel.com>
>
> Hmm, rather than supporting that in the core, I'd prefer to have the
> driver pass an empty function instead. Then, in the driver, we can have
> a comment explaining the special situation.

Agree. This seems a better idea forcing the user to explain the situation :).
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diff mbox

Patch

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);