Hi Peter,
On 5/6/24 11:26 PM, Peter Rosin wrote:
Hi!
Regarding the subject (and elsewhere) I think of "mux core" as roughly
the code in the i2c-mux.c file. So, for me, the "mux core" does not have
an address, it is a mux "driver instance" or "device" that sits on the
I2C address that you need to share.
I'm the one who suggested mux core here (privately) :)
The issue is that in my head a mux device is the i2c adapter/bus (from
i2c-mux.yaml dt binding example):
"""
i2c {
#address-cells = <1>;
#size-cells = <0>;
i2c-mux@70 {
compatible = "nxp,pca9548";
reg = <0x70>;
#address-cells = <1>;
#size-cells = <0>;
i2c@3 {
#address-cells = <1>;
#size-cells = <0>;
reg = <3>;
gpio@20 {
compatible = "nxp,pca9555";
gpio-controller;
#gpio-cells = <2>;
reg = <0x20>;
};
};
i2c@4 {
#address-cells = <1>;
#size-cells = <0>;
reg = <4>;
gpio@20 {
compatible = "nxp,pca9555";
gpio-controller;
#gpio-cells = <2>;
reg = <0x20>;
};
};
};
};
"""
"mux core" here would refer to i2c-mux@70, "mux device"/"mux" i2c@3 or
i2c@4. E.g. when I'm saying "in mux 3", I'm talking about i2c@3 here.
For me a driver instance is a device, so "mux driver instance" would be
a "mux device". Ah... naming is hard. Anyway, up to you, I just wanted
to make sure we're talking about the same thing and there's no confusion
here.
[...]
I also wonder if that second condition (...->type == &i2c_client_type) should
be a WARN_ON_ONCE? I don't see how the flag can be set sanely on an adapter
that is not itself an I2C client. Can it?
Agreed, good suggestion here... Though...
https://lwn.net/Articles/969923/ it seems new additions of WARN_ON are
now discouraged? Not looking to start a discussion here about whether
WARN_ON is good or bad, merely pointing at this if it was missed somehow.
+
+ if (!quirks)
+ return -ENOMEM;
+
+ if (parent->quirks)
+ memcpy(quirks, parent->quirks, sizeof(*quirks));
+
+ quirks->flags |= I2C_AQ_SKIP_ADDR_CHECK;
+ quirks->skip_addr_in_parent = client->addr;
+ priv->adap.quirks = quirks;
The I2C_AQ_SKIP_ADDR_CHECK flag should probably not be propagated?
Oh... you mean if we have a mux on an i2c adapter of a mux and the
adapters handled by the parent mux have SKIP_ADDR set and we don't want
the adapters handled by the leaf mux to have this flag as well? Is that
what you meant?
Cheers,
Quentin
