On 03/19/2015 04:09 AM, Wolfram Sang wrote:
Possible. But this change just makes i2c-mux-pinctrl honor status
property at all. There is no functional change except it now allows
you to disable any of the sub-busses.
Actually, this is the feature I like. However, I wonder if we shouldn't
have that in the core, say in of_i2c_register_devices()?
Hmm, looking at of_i2c_register_devices():
for_each_available_child_of_node(adap->dev.of_node, node)
of_i2c_register_device(adap, node);
already honors status properties by using for_each_available_foo.
Therefore, i2c-core will also skip i2c device nodes disabled by
status property.
Yes, but only child nodes, not the complete bus. Here is an RFC of what
I mean:
From: Wolfram Sang <wsa@xxxxxxxxxxxxx>
Subject: [RFC] i2c: of: always check if busses are enabled
Allow all busses to have a "status" property which allows busses to not
be probed when set to "disabled". Needed for DTS overlays with i2c mux
scenarios.
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
@@ -1305,8 +1305,8 @@ static void of_i2c_register_devices(struct i2c_adapter *adap)
{
struct device_node *node;
- /* Only register child devices if the adapter has a node pointer set */
- if (!adap->dev.of_node)
+ /* Only register childs if adapter has a node pointer with enabled status */
+ if (!adap->dev.of_node || !of_device_is_available(adap->dev.of_node))
return;
That feels a bit odd to me. For a regular non-mux I2C controller, that
extra case would never trigger if the controller node was disabled,
since the device core would never probe the controller device itself.
So, we'd end up with inconsistent paths through the I2C core for regular
controllers and muxes.
Perhaps better would be to have a mux-specific function to iterate over
a mux's child nodes and instantiate buses for those. That function would
check whether each bus node was disabled or not. That'd isolate the
special case into the place where it was relevant.
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