Wulfie:
I am not an expert at Device Tree stuff, but this is what I think I know.
I2C-0 is intended for internal board management, so sort of reserved,
except as a last resort.
I2C-1 is available, but not enabled, on the BBB and is enabled/implemented
on the PocketBeagle, so you could always look at the PocketBeagle
implementation.
The I2C-1 pins are default assigned to other things, so they will need to
be re-assigned to the I2C-1 peripheral if used.
It would make sense that I2C-1 was not enabled, if not used by default on
the BBB.
I2C-2 is enabled/implemented on the BBB and the PocketBeagle. It is the
primary bus for cape memory access, so it is always there.
The DTB you were looking at seems to have an off-by-one number assignment,
with respect to the bus numbers used by Linux.
I don't understand why or how.
There was a definite off-by-one issue with the I2C bus assignments for
Debian 7 and prior.
--- Graham
==
On Saturday, February 10, 2018 at 4:27:17 PM UTC-6, Wulf Man wrote:
>
> I will keep looking into this.
> more infos
>
> I took the current DTB file and decompiled it
> I looked at the I2C sections
>
> i2c0 = "/ocp/i2c@44e0b000";
> i2c1 = "/ocp/i2c@4802a000";
> i2c2 = "/ocp/i2c@4819c000";
>
>
> i2c@44e0b000 {
> compatible = "ti,omap4-i2c";
> #address-cells = <0x1>;
> #size-cells = <0x0>;
> ti,hwmods = "i2c1";
> reg = <0x44e0b000 0x1000>;
> interrupts = <0x46>;
> status = "okay";
> pinctrl-names = "default";
> pinctrl-0 = <0x32>;
> clock-frequency = <0x61a80>;
> linux,phandle = <0xa0>;
> phandle = <0xa0>;
>
>
> with PMIC infos below this
>
>
> i2c@4802a000 {
> compatible = "ti,omap4-i2c";
> #address-cells = <0x1>;
> #size-cells = <0x0>;
> ti,hwmods = "i2c2";
> reg = <0x4802a000 0x1000>;
> interrupts = <0x47>;
> status = "disabled";
> <--------------------------- anybody know why this is listed as disabled
> ?
> linux,phandle = <0xa9>;
> phandle = <0xa9>;
>
> nothing below this as the processor pins are not connected to anything
> except
> "P9.18", /* i2c1_sda */ "P9.17", /* i2c1_scl */
>
>
> i2c@4819c000 {
> compatible = "ti,omap4-i2c";
> #address-cells = <0x1>;
> #size-cells = <0x0>;
> ti,hwmods = "i2c3";
> reg = <0x4819c000 0x1000>;
> interrupts = <0x1e>;
> status = "okay";
> pinctrl-names = "default";
> pinctrl-0;
> clock-frequency = <0x186a0>;
> linux,phandle = <0xaa>;
> phandle = <0xaa>;
>
> With cape eprom infos below.
>
> It would seem to me that even though we have a /dev/I2C-1 its somehow
> not enabled for use
> IF i do a i2cdetect and grep dmesg it just repeats a bus timeout
>
> I am at a dead end on this for my knowledge any help would be appreciated
>
>
>
>
>
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