On Fri, Jun 2, 2017 at 4:34 PM, jhalpin100 <[email protected]> wrote:
> I'm trying to set the bus speed for i2c-2 to 400000. I'm running kernel
> 4.4.68-ti-r107 on a Beaglebone Black. So farI've tried
>
> 1. modifying am335x-boneblack.dtb to set the speed to 400000
>
> 2. recompiling the kernel (after modifying i2c-core.c).
> in i2c_parse_fw_timings() i set t->bus_freq to 400000 explicitly.
>
> Neither of these had any affect on the bus speed.
>
> I've been searching for a couple days, and can't see another way to do it,
> can the bus speed actually be changed somehow?
Have you verified that you are atleast booting the same *.dtb that you
are modifiing:
You can check the live tree via:
root@beaglebone:~# fdtdump /sys/firmware/devicetree/base/ocp/i2c@4802a000/
/* dump of live tree at /sys/firmware/devicetree/base/ocp/i2c@4802a000 */
/ {
reg = <0x4802a000 0x00001000>;
name = "i2c";
interrupts = <0x00000047>;
pinctrl-0;
compatible = "ti,omap4-i2c";
clock-frequency = <0x000186a0>;
status = "okay";
#address-cells = <0x00000001>;
ti,hwmods = "i2c2";
phandle = <0x000000a9>;
#size-cells = <0x00000000>;
pinctrl-names = "default";
linux,phandle = <0x000000a9>;
};
and then i2c2's bus frequency:
root@beaglebone:~# dmesg | grep i2c | grep 4802a000
[ 42.615491] omap_i2c 4802a000.i2c: bus 1 rev0.11 at 100 kHz
Regards,
--
Robert Nelson
https://rcn-ee.com/
--
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