linux-kernel - Re: [PATCH 2/3] usb: gadget: composite: Split composite reset and disconnect

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Date:   Fri, 8 Jan 2021 00:35:59 -0800
From:   Jack Pham <jackp@...eaurora.org>
To:     Thinh Nguyen <Thinh.Nguyen@...opsys.com>
Cc:     Felipe Balbi <balbi@...nel.org>,
        Wesley Cheng <wcheng@...eaurora.org>,
        "peter.chen@....com" <peter.chen@....com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>
Subject: Re: [PATCH 2/3] usb: gadget: composite: Split composite reset and
 disconnect

Hi Thinh,

On Fri, Jan 08, 2021 at 02:19:30AM +0000, Thinh Nguyen wrote:
> Hi Wesley,
> 
> Felipe Balbi wrote:
> > Hi,
> >
> > Wesley Cheng <wcheng@...eaurora.org> writes:
> >> +void composite_reset(struct usb_gadget *gadget)
> >> +{
> >> +	/*
> >> +	 * Section 1.4.13 Standard Downstream Port of the USB battery charging
> >> +	 * specification v1.2 states that a device connected on a SDP shall only
> >> +	 * draw at max 100mA while in a connected, but unconfigured state.
> > The requirements are different, though. I think OTG spec has some extra
> > requirements where only 8mA can be drawn max. You need to check for the
> > otg flag. Moreover, USB3+ spec has units of 150mA meaning the device
> > can't draw 100mA (IIRC).
> >
> 
> We see issue with this patch series. For our device running at SSP, the
> device couldn't recover from a port reset and remained in eSS.Inactive
> state.
> 
> This patch series is already in Greg's usb-testing. Please review and
> help fix it.
> 
> We can see the failure once the patch "usb: gadget: configfs: Add a
> specific configFS reset callback" is introduced.

Hmm. Does your device use a legacy USB2 PHY (not generic PHY) driver,
and does it implement the usb_phy_set_power() callback? Because
otherwise this new configfs_composite_reset() callback would not have
changed from the original behavior since the newly introduced (in patch
1/3) dwc3_gadget_vbus_draw() callback would simply be a no-op if
dwc->usb2_phy is not present.

If it does turn out to be something with your PHY driver's set_power(),
it's still puzzling since it's directed to only the usb2_phy, so I'm
curious how telling it to draw 100mA could affect SSP operation at all.

Thanks,
Jack
-- 
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