Thread (12 messages) 12 messages, 5 authors, 2021-01-08

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

From: Jack Pham <hidden>
Date: 2021-01-08 08:36:52
Also in: lkml

Hi Thinh,

On Fri, Jan 08, 2021 at 02:19:30AM +0000, Thinh Nguyen wrote:
Hi Wesley,

Felipe Balbi wrote:
quoted
Hi,

Wesley Cheng [off-list ref] writes:
quoted
+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
-- 
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project
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