Setting up i2c on bbb using device tree: error: could not find pctldev for node

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1

I’m trying to set up i2c on the beaglebone black with a yocto build of v3.19.3.

My dts contains

`

&i2c1 {
status = “okay”;
pinctrl-names = “default”;
pinctrl-0 = <&i2c1_pins>;
clock-frequency = <100000>;
};
`

and …

`
&am33xx_pinmux {
…
i2c1_pins: pin_mux_i2c1_pins {
pinctrl-single,pins = <
0x158 (PIN_INPUT_PULLUP | SLEWCTRL_FAST | MUX_MODE2) /* spi0_d1.i2c1_sda, P9_18 /
0x15C (PIN_INPUT_PULLUP | SLEWCTRL_FAST | MUX_MODE2) / spi0_cs0.i2c1_scl, P9_17 */

;
};
…
};

`

When I boot I get this error in the log

`
[ 1.506928] omap_i2c 44e0b000.i2c: could not find pctldev for node /pinmux@44e10800/pinmux_i2c0_pins, deferring probe
[ 1.517979] platform 44e0b000.i2c: Driver omap_i2c requests probe deferral
[ 1.525177] omap_i2c 4802a000.i2c: could not find pctldev for node /pinmux@44e10800/i2c1_pins, deferring probe
[ 1.535576] platform 4802a000.i2c: Driver omap_i2c requests probe deferral
[ 1.542751] omap_i2c 4819c000.i2c: could not find pctldev for node /pinmux@44e10800/i2c2_pins, deferring probe
[ 1.553146] platform 4819c000.i2c: Driver omap_i2c requests probe deferral

`

How do I debug this error?

2

"requests probe deferral" means it's waiting for something.. aka
pinctrl driver, maybe a clock, etc.. Essentially at "1.553146" the
i2c was not 'ready'..

Regards,

3

Thanks so much for the quick reply - I’ll have to look into how to defer this to later in the bootup.

4

Hey Matthew,

I had the same problem you’re having when trying to use the I2C bus. After spending days debugging and trying to find a solution on the internet I stumbled upon this.

In summary; the i2c-dev module needs to be loaded, and the I2C buses will appear under /dev/i2c*. This can be done as;

sudo modprobe i2c-dev

Appears to be a bug with the kernel, I am running Linux arm 4.1.0-rc4-bone2, after following Robert Nelsons wiki page for linux on arm as found here.

Hopefully this assists other people with the same problem in the future.

Cheers,
Eric

5

Yeap it was, fixed in rc6-bone6 :wink:

https://github.com/RobertCNelson/bb-kernel/commit/cb3dca3fe73f5ede131643943541405d8360c859

Regards,