Hi Frieder,
On Thu, Sep 20, 2018 at 10:52 AM Frieder Schrempf
<frieder.schrempf@xxxxxxxxx> wrote:
>
> Hi,
>
> I have a question concerning the setup for a board with an onboard USB
> hub. The SoC (i.MX6S) is expected to provide a 12 MHz clock on one of
> the clock output pins as a reference for the USB hub.
>
> Now I was looking for a way to configure this in the DT, which works
> fine up to the point, that there doesn't seem to be a way to set a
> reference clock for a generic USB device.
>
> Would it make sense to implement the enabling/disabling of the clock in
> the generic USB device driver?
> It doesn't seem right to write a separate driver for the hub only to
> turn the clock on and off.
>
> My intended DT setup would look something like this:
>
> &usbh1 {
> vbus-supply = <®_usb_h1_vbus>;
> pinctrl-names = "default";
> pinctrl-0 = <&pinctrl_usbh1>;
> dr_mode = "host";
> status = "okay";
> #address-cells = <1>;
> #size-cells = <0>;
>
> hub@1 {
> compatible = "usb4b4,6570";
> reg = <1>;
> clocks = <&clks IMX6QDL_CLK_CKO>;
> assigned-clocks = <&clks IMX6QDL_CLK_CKO>,
> <&clks IMX6QDL_CLK_CKO2_SEL>,
> <&clks IMX6QDL_CLK_CKO2>;
> assigned-clock-parents = <&clks IMX6QDL_CLK_CKO2>,
> <&clks IMX6QDL_CLK_OSC>,
> <&clks IMX6QDL_CLK_CKO2_PODF>;
> assigned-clock-rates = <0 0 12000000>;
> }
> };
Peter Chen has tried to implement such support:
https://lkml.org/lkml/2017/6/21/88
However it still needs some work so that it can be accepted in mainline.
