From: Dejin Zheng <zhengdejin5@gmail.com>
To: Felipe Balbi <balbi@kernel.org>
Cc: gregkh@linuxfoundation.org, linux-usb@vger.kernel.org,
linux-kernel@vger.kernel.org,
Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Subject: Re: [PATCH v3] usb: dwc3: core: fix a issue about clear connect state
Date: Wed, 28 Oct 2020 22:43:15 +0800 [thread overview]
Message-ID: <20201028144315.GA3766@nuc8i5> (raw)
In-Reply-To: <87y2jqlahc.fsf@kernel.org>
On Wed, Oct 28, 2020 at 03:57:03PM +0200, Felipe Balbi wrote:
>
> Hi,
>
> Dejin Zheng <zhengdejin5@gmail.com> writes:
> >> Dejin Zheng <zhengdejin5@gmail.com> writes:
> >> > According to Synopsys Programming Guide chapter 2.2 Register Resets,
> >> > it cannot reset the DCTL register by setting DCTL.CSFTRST for core soft
> >> > reset, if DWC3 controller as a slave device and stay connected with a usb
> >> > host, then, while rebooting linux, it will fail to reinitialize dwc3 as a
> >> > slave device when the DWC3 controller did not power off. because the
> >> > connection status is incorrect, so we also need to clear DCTL.RUN_STOP
> >> > bit for disabling connect when doing core soft reset. There will still
> >> > be other stale configuration in DCTL, so reset the other fields of DCTL
> >> > to the default value 0.
> >>
> >> This commit log is a bit hard to understand. When does this problem
> >> actually happen? It seems like it's in the case of, perhaps, kexecing
> >> into a new kernel, is that right?
> >>
> > It happens when entering the kernel for the second time after the reboot
> > command.
> >
> >> At the time dwc3_core_soft_reset() is called, the assumption is that
> >> we're starting with a clean core, from power up. If we have stale
> >> configuration from a previous run, we should fix this on the exit
> >> path. Note that if we're reaching probe with pull up connected, we
> >> already have issues elsewhere.
> >>
> >> I think this is not the right fix for the problem.
> >>
> > I think you are right, Thinh also suggested me fix it on the exit path
> > in the previous patch v2. Do you think I can do these cleanups in the
> > shutdown hook of this driver? Balbi, is there a more suitable place to
> > do this by your rich experience? Thanks!
>
> I don't think shutdown is called during removal, I'm not sure. I think
> we had some fixes done in shutdown time, though. Test it out, but make
> sure there are no issues with a regular modprobe cycle.
>
Balbi, thanks for your suggestions, I will do a test in the shutdown
hook first.
> --
> balbi
next prev parent reply other threads:[~2020-10-28 22:27 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-20 13:58 [PATCH v3] usb: dwc3: core: fix a issue about clear connect state Dejin Zheng
2020-10-27 8:33 ` Felipe Balbi
2020-10-28 13:46 ` Dejin Zheng
2020-10-28 13:57 ` Felipe Balbi
2020-10-28 14:43 ` Dejin Zheng [this message]
2020-10-30 15:15 ` Dejin Zheng
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=20201028144315.GA3766@nuc8i5 \
--to=zhengdejin5@gmail.com \
--cc=Thinh.Nguyen@synopsys.com \
--cc=balbi@kernel.org \
--cc=gregkh@linuxfoundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-usb@vger.kernel.org \
/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).