Re: [PATCH] usb: dwc3: gadget: Inform system of suspended state
From: Krishna Kurapati PSSNV
Date: Tue Jun 04 2024 - 04:52:49 EST
On 6/4/2024 1:55 PM, Mike Looijmans wrote:
On 04-06-2024 08:45, Krishna Kurapati PSSNV wrote:
On 6/4/2024 10:56 AM, Mike Looijmans wrote:
On 04-06-2024 03:03, Thinh Nguyen wrote:
Hi,
On Mon, Jun 03, 2024, Mike Looijmans wrote:
When disconnecting the USB cable on an LS1028 device, nothing happens
in userspace, which keeps thinking everything is still up and running.
Turns out that the DWC3 controller only sends
DWC3_DEVICE_EVENT_SUSPEND
in that case, and not a DWC3_DEVICE_EVENT_DISCONNECT as one would
expect. As a result, sysfs attribute "state" remains "configured"
until something resets it.
Forward the "suspended" state to sysfs, so that the "state" at least
changes into "suspended" when one removes the cable, and hence also
matches the gadget's state when really suspended.
On disconnection, did you see disconnect interrupt? If so, it should
transition to USB_STATE_NOATTACHED. This change doesn't seem to
directly
address your issue. Can you provide the driver tracepoints?
The device doesn't issue a disconnect event, I didn't have tracing
enabled in the kernel but added some dev_info() calls to determine
what was going on. Added this to dwc3_process_event_entry():
dev_info(dwc->dev, "event: 0x%x type=0x%x", event->raw,
event->type.type);
When disconnecting the cable from the host, I see this:
[ 50.841411] dwc3 3110000.usb: event: 0x6084 type=0x42
[ 50.841457] dwc3 3110000.usb: event: 0x4086 type=0x43
[ 50.841494] dwc3 3110000.usb: event: 0x6084 type=0x42
[ 50.841534] dwc3 3110000.usb: event: 0x4086 type=0x43
[ 50.841571] dwc3 3110000.usb: event: 0x4086 type=0x43
[ 52.650990] dwc3 3110000.usb: event: 0x30601 type=0x0
The "0x4086" and "0x6084" messages are endpoint events that occur all
the time while connected. The last event is the "suspend" one. After
that, total silence.
If you need traces, please point me to a description on how to obtain
them.
Hi Mike,
I may be wrong, but can you help understand the mechanism as to how
disconnect interrupt is generated in your targets. For example, on QC
SoC's, this happens when HS_PHY_CTRL reg VBUS_VALID bit is cleared and
cable is disconnected. This is because the vbus line is not routed to
controller. But from my calls with Synopsys previously, I remember
that the vbus line is routed to the controller as well for other OEMs.
In your SoC, what is the indication to controller that vbus is absent ?
The board I'm testing this on is an LS1028ARDB. Looking at the
schematic, VBUS is routed to the chip. There's also an LED attached to
it, which turns off when I unplug the cable.
In the devicetree, I can't see any hint of NXP-specific "glue" in the
DWC3 entries, so it uses the controller "as is":
compatible = "fsl,ls1028a-dwc3", "snps,dwc3";
reg = <0x0 0x3100000 0x0 0x10000>;
snps,dis_rxdet_inp3_quirk;
snps,quirk-frame-length-adjustment = <0x20>;
snps,incr-burst-type-adjustment = <1>, <4>,
<8>, <16>;
The "fsl,ls1028a-dwc3" keyword doesn't actually occur anywhere in the
kernel, so it uses plain "snps,dwc3".
Also, after this happens, do you see the next plug in working ?
Next plugin works, because of a "reset" event at that point that makes
everything happy again.
Ahh, got it. Thanks for the info.
I ran into a similar issue before where disconnect isn't generated [1]
and was suspecting it could be the case here but it isn't.
[1]:
https://patchwork.kernel.org/project/linux-usb/patch/20231011100214.25720-1-quic_kriskura@xxxxxxxxxxx/
Regards,
Krishna,
The state remains in "configured" while the cable is out. Plugging the
cable back in makes it revert to "default" first, then it goes back into
"configured".