Re: [PATCH v3 2/2] usb: gadget: composite: Draw 100mA current if not configured

[Prashanth K]

On 25-02-23 12:08 am, Thinh Nguyen wrote:
> On Fri, Feb 24, 2023, Prashanth K wrote:
> > On 24-02-23 01:40 am, Thinh Nguyen wrote:
> > > On Thu, Feb 23, 2023, Prashanth K wrote:
> > > > Currently we don't change the current value if device isn't in
> > > > configured state. But the battery charging specification says,
> > >
> > > Can you provide the spec section also?
> > 1.2 Background
> > 1.4.13 Standard Downstream Port
> >
> > Did you mean to add these in the commit message?
>
> Yes, it's better to have the reference in case we need to revisit this.
I have added it in v4 patch, thanks for pointing it out.
> > > > device can draw up to 100mA of current if its in unconfigured
> > >
> > > Is this related to being self-powered?
>
> > I think its applicable for bus-powered devices.
>
> No, I mean before configured state, is the device considered
> self-powered? Since being self-powered means drawing 100mA or less, we
> can use USB_SELF_POWER_VBUS_MAX_DRAW to provide more context. If it's
> totally unrelated, then you can ignore this.
>
> Thanks,
> Thinh
As per my understanding, those are 2 different things. A self-powered 
device isn't allowed to draw more than 100mA. And an unconfigured device
isn't allowed to draw more than 100mA (in HS). One thing that I recently 
found out is that, as per usb3.0 spec, SS device can only draw up to 
150mA if its unconfigured state. So i have to check the speed and set 
the current values accordingly.

Thanks,
Prashanth K