On 03/08/2013 05:45 PM, Marc Kleine-Budde wrote:
> On 03/08/2013 11:46 AM, Marc Kleine-Budde wrote:
>> On 02/04/2013 04:58 PM, Roger Quadros wrote:
>>> The PHY clock, clock rate, VCC regulator and RESET regulator
>>> can now be provided via device tree.
>>>
>>> Signed-off-by: Roger Quadros <rogerq@xxxxxx>
>>> ---
>>> .../devicetree/bindings/usb/usb-nop-xceiv.txt | 34 ++++++++++++++++++++
>>> drivers/usb/otg/nop-usb-xceiv.c | 31 ++++++++++++++++++
>>> 2 files changed, 65 insertions(+), 0 deletions(-)
>>> create mode 100644 Documentation/devicetree/bindings/usb/usb-nop-xceiv.txt
>>>
>>> diff --git a/Documentation/devicetree/bindings/usb/usb-nop-xceiv.txt b/Documentation/devicetree/bindings/usb/usb-nop-xceiv.txt
>>> new file mode 100644
>>> index 0000000..d7e2726
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/usb/usb-nop-xceiv.txt
>>> @@ -0,0 +1,34 @@
>>> +USB NOP PHY
>>> +
>>> +Required properties:
>>> +- compatible: should be usb-nop-xceiv
>>> +
>>> +Optional properties:
>>> +- clocks: phandle to the PHY clock. Use as per Documentation/devicetree
>>> + /bindings/clock/clock-bindings.txt
>>> + This property is required if clock-frequency is specified.
>>> +
>>> +- clock-names: Should be "main_clk"
>>> +
>>> +- clock-frequency: the clock frequency (in Hz) that the PHY clock must
>>> + be configured to.
>>> +
>>> +- vcc-supply: phandle to the regulator that provides RESET to the PHY.
>>> +
>>> +- reset-supply: phandle to the regulator that provides power to the PHY.
>>> +
>>> +Example:
>>> +
>>> + hsusb1_phy {
>>> + compatible = "usb-nop-xceiv";
>>> + clock-frequency = <19200000>;
>>
>> Why do you hardcode the clock frequency here? You should use
>> clk_get_rate() to get the frequency from the clock tree.
>
> What about declaring a "fixed-clock" node in the device tree? Then it
> should be possible to keep the driver free of any omap specific code.
>
The current implementation is not OMAP specific and is not limited to a
fixed frequency clock. The PHY driver is using standard clock APIs to set
the clock rate 'only' if the 'clock-frequency' property is present in the
device tree node.
What is the benefit of declaring it as a "fixed-clock"?
FYI. The clock may not necessarily be a fixed frequency clock and someone
needs to program the rate.
cheers,
-roger
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