Hi Fabio,
On 25.10.18 15:20, Fabio Estevam wrote:
> 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.
Thank you for pointing that out. This looks like a rather complex
framework, trying to handle all kinds of generic clock and power setups.
For my use case it would be enough to add handling of a single reference
clock to the USB device driver.
Thanks,
Frieder
