[PATCH] common: usb-hub: Reset hub port before scanning

[Marek Vasut]

On 11/20/23 00:03, Shantur Rathore wrote:
> Hi Marek,

Hi,

> On Sun, Nov 19, 2023 at 8:53 PM Marek Vasut <marex at denx.de> wrote:
>>
>> On 11/10/23 15:13, Shantur Rathore wrote:
>>> Currently when a hub is turned on, all the ports are powered on.
>>> This works well for hubs which have individual power control.
>>>
>>> For the hubs without individual power control this has no effect.
>>
>> OK
>>
>>> Mostly in these scenarios the hub port is powered before the USB
>>> controller is enabled, this can lead to some devices in unexpected
>>> state.
>>
>> This ^ part needs clarification.
>>
>> Which devices are in incorrect state, the ones connected to the hub
>> downstream facing ports ?
>>
> 
> In my case RockPro64, the power to usb ports onboard is controlled by
> a regulator.
> This regulator is enabled as part of init  as here
> https://github.com/u-boot/u-boot/blob/master/arch/arm/dts/rk3399-rockpro64.dtsi#L177
> 
> On init, the usb devices connected to the port are powered up, in my
> case AM8180 (a RTL9210 based ) NVMe to USB enclosure with UAS.
> But the usb controller is only enabled at 'usb start' and by this time
> the device is in some state that it doesn't get detected.
> 
> One way to make sure the devices connected to the ports are in an
> initialising state is by issuing a port reset before scanning the
> port.

Why not remove this regulator-always-on and let the PHY driver turn the 
VBUS ON only when it is needed ?

Wouldn't that solve the problem too AND remove unnecessarily enabled 
regulator ?

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