On 06.07.2017 19:46, Stephen Warren wrote:
> On 07/05/2017 07:24 PM, Peter Chen wrote:
>> On Wed, Jul 05, 2017 at 08:19:53PM +0300, Dmitry Osipenko wrote:
>>> From: Thierry Reding <treding@xxxxxxxxxx>
>>>
>>> Override the compatible string of the first USB controller to enable
>>> device mode.
>>>
>>> Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
>>> ---
>>> arch/arm/boot/dts/tegra20-trimslice.dts | 2 ++
>>> 1 file changed, 2 insertions(+)
>>>
>>> diff --git a/arch/arm/boot/dts/tegra20-trimslice.dts
>>> b/arch/arm/boot/dts/tegra20-trimslice.dts
>>> index b902ab594afa..96b4f3f9827b 100644
>>> --- a/arch/arm/boot/dts/tegra20-trimslice.dts
>>> +++ b/arch/arm/boot/dts/tegra20-trimslice.dts
>>> @@ -336,7 +336,9 @@
>>> };
>>> usb@c5000000 {
>>> + compatible = "nvidia,tegra20-udc";
>>> status = "okay";
>>> + dr_mode = "otg";
>>
>> If this board supports peripheral-only, you need to
>> set dr_mode as "peripheral".
>
> I agree here. Even if the ports can theoretically do otg, and DT is supposed to
> represent HW not SW, given we have no SW support for actual OTG, it'd be best
> not to change the DT to OTG until it's actually useful to do so. This comment
> applies to the patches I ack'd already too.
In case of absence of the "dr_mode" option or without a support of host mode
switching, UDC driver fallbacks to the peripheral mode. Given that DT is
supposed to be stable, I'm not sure what to do... should I specify the
peripheral mode for now (which doesn't represent the HW) or completely remove
the "dr_mode"?
--
Dmitry
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