From: Felipe Balbi <balbi@kernel.org>
To: Michael Grzeschik <mgr@pengutronix.de>
Cc: lars@metafoo.de, alexandru.Ardelean@analog.com,
linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
gregkh@linuxfoundation.org, bigeasy@linutronix.de,
m.olbrich@pengutronix.de, kernel@pengutronix.de
Subject: Re: [PATCH] usb: dwc3: gadget: don't dequeue requests on already disabled endpoints
Date: Mon, 30 Mar 2020 10:18:57 +0300 [thread overview]
Message-ID: <87sghq2tum.fsf@kernel.org> (raw)
In-Reply-To: <20200329190244.GK27849@pengutronix.de>
[-- Attachment #1: Type: text/plain, Size: 2421 bytes --]
Hi,
Michael Grzeschik <mgr@pengutronix.de> writes:
>> > dwc3_gadget_ep_disable gets called before the last request gets
>> > dequeued.
>> >
>> > In __dwc3_gadget_ep_disable all started, pending and cancelled
>> > lists for this endpoint will call dwc3_gadget_giveback in
>> > dwc3_remove_requests.
>> >
>> > After that no list containing the afterwards dequed request,
>> > therefor it is not necessary to run the dequeue routine.
>> >
>> > Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
>> > ---
>> > @Lars-Peter Clausen:
>> >
>> > This patch addresses the case that not queued requests get dequeued.
>> > The only case that this happens seems on disabling the gadget.
>> >
>> > drivers/usb/dwc3/gadget.c | 3 +++
>> > 1 file changed, 3 insertions(+)
>> >
>> > diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
>> > index 9a6f741d1db0dc..5d4fa8d6c93e49 100644
>> > --- a/drivers/usb/dwc3/gadget.c
>> > +++ b/drivers/usb/dwc3/gadget.c
>> > @@ -1609,6 +1609,9 @@ static int dwc3_gadget_ep_dequeue(struct usb_ep *ep,
>> >
>> > trace_dwc3_ep_dequeue(req);
>> >
>> > + if (!(dep->flags & DWC3_EP_ENABLED))
>> > + return 0;
>>
>> which driver is trying to call dequeue after the endpoint is disabled?
>> Got some tracepoints of the problem happening?
>
> I see the case when using uvc-gadget.
>
> Look into uvc_v4l2_release in uvc_v4l2.c:
>
> uvc_function_disconnect
> composite_disconnect
> reset_config
> uvc_function_disable->usb_ep_disable
>
> uvcg_video_enable
> usb_ep_dequeue
> dwc3_gadget_ep_dequeue
Oh, I see what you mean. We get a disconnect, which disables the
endpoints, which forces all requests to be dequeued. Now I remember why
this exists: we giveback the requests from disconnect because not all
gadget drivers will call usb_ep_dequeue() if simply told about the
disconnect. Then UDC drivers have to be a little more careful and make
sure that all requests are givenback.
In any case, why is it a problem to call usb_ep_dequeue()? Is it only
because of that dev_err()? We could just remove that message,
really. Eventually, I want to move more of this logic into UDC core so
udc drivers can be simplified. For that work, though, first we would
have to add a "generic" struct usb_ep_hw implementation and manage list
of requests as part of UDC core as well.
--
balbi
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 832 bytes --]
next prev parent reply other threads:[~2020-03-30 7:19 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-06 14:45 [PATCH] usb: dwc3: gadget: Handle dequeuing of non queued URB gracefully Alexandru Ardelean
2019-11-12 14:41 ` Michael Olbrich
2020-01-16 11:12 ` Ardelean, Alexandru
2020-01-16 13:05 ` Felipe Balbi
2020-01-16 13:24 ` [PATCH][RESEND] " Alexandru Ardelean
2020-01-30 12:02 ` Felipe Balbi
2020-03-10 13:22 ` Ardelean, Alexandru
2020-03-10 13:45 ` Lars-Peter Clausen
2020-03-10 14:07 ` Lars-Peter Clausen
2020-03-27 8:43 ` [PATCH] usb: dwc3: gadget: don't dequeue requests on already disabled endpoints Michael Grzeschik
2020-03-27 8:53 ` Sergei Shtylyov
2020-03-27 11:15 ` Andy Shevchenko
2020-03-27 9:14 ` Lars-Peter Clausen
2020-03-27 10:43 ` Michael Grzeschik
2020-03-27 10:55 ` Lars-Peter Clausen
2020-03-28 8:27 ` Felipe Balbi
2020-03-29 19:02 ` Michael Grzeschik
2020-03-30 7:18 ` Felipe Balbi [this message]
2020-03-30 8:25 ` Michael Grzeschik
2020-03-30 10:06 ` Felipe Balbi
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87sghq2tum.fsf@kernel.org \
--to=balbi@kernel.org \
--cc=alexandru.Ardelean@analog.com \
--cc=bigeasy@linutronix.de \
--cc=gregkh@linuxfoundation.org \
--cc=kernel@pengutronix.de \
--cc=lars@metafoo.de \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-usb@vger.kernel.org \
--cc=m.olbrich@pengutronix.de \
--cc=mgr@pengutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).