Hi Justin!
The initial device tree changed between kernel 3.8 and 4.x. In 4.x the
Control Module register *pwmss_ctrl* (@664h) gets cleared at boot. This
register can get used to sychronize several PWM subsystems. A feature that
isn't supported by the kernel nor by any of it's drivers. So no reason to
change the initial state and clear that register. This just disables all
PWM subsystems and makes kernel versions incompatible. (You may call it an
official kernel virus).
Anyway, in order to get the PWM subsystems working in kernel 4.x you have
to make sure that the register doesn't get cleared at boot. Ie. you can
invert the bit-logic. Therefor download the device tree sources, edit file
*am33xx-clocks.dtsi*, find the following nodes and make them look like (=
add tag *ti,set-bit-to-disable)*
ehrpwm0_tbclk: ehrpwm0_tbclk@44e10664 {
#clock-cells = <0>;
compatible = "ti,gate-clock";
clocks = <&l4ls_gclk>;
ti,bit-shift = <0>;
ti,set-bit-to-disable;
reg = <0x0664>;
};
ehrpwm1_tbclk: ehrpwm1_tbclk@44e10664 {
#clock-cells = <0>;
compatible = "ti,gate-clock";
clocks = <&l4ls_gclk>;
ti,bit-shift = <1>;
ti,set-bit-to-disable;
reg = <0x0664>;
};
ehrpwm2_tbclk: ehrpwm2_tbclk@44e10664 {
#clock-cells = <0>;
compatible = "ti,gate-clock";
clocks = <&l4ls_gclk>;
ti,bit-shift = <2>;
ti,set-bit-to-disable;
reg = <0x0664>;
};
Then compile and install the binary trees. PWM subsystems will work after
reboot.
Regards
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