linux-kernel - Re: [PATCH v4 3/9] usb: dwc3: Increase timeout for CmdAct cleared by device controller

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Message-ID: <CAKgpwJVU9m6G8PRdray2fGCp_peOU9C-ZAVKTk7pmSdq6z4NiA@mail.gmail.com>
Date:   Fri, 8 May 2020 20:22:21 +0800
From:   Jun Li <lijun.kernel@...il.com>
To:     John Stultz <john.stultz@...aro.org>
Cc:     Felipe Balbi <balbi@...nel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Yu Chen <chenyu56@...wei.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        ShuFan Lee <shufan_lee@...htek.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Chunfeng Yun <chunfeng.yun@...iatek.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Valentin Schneider <valentin.schneider@....com>,
        Jack Pham <jackp@...eaurora.org>,
        Linux USB List <linux-usb@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>
Subject: Re: [PATCH v4 3/9] usb: dwc3: Increase timeout for CmdAct cleared by
 device controller

Jun Li <lijun.kernel@...il.com> 于2020年5月7日周四 上午11:08写道：
>
> John Stultz <john.stultz@...aro.org> 于2020年5月7日周四 上午6:27写道：
> >
> > On Wed, May 6, 2020 at 2:00 AM Jun Li <lijun.kernel@...il.com> wrote:
> > > John Stultz <john.stultz@...aro.org> 于2019年10月30日周三 上午5:18写道：
> > > > On Tue, Oct 29, 2019 at 2:11 AM Felipe Balbi <balbi@...nel.org> wrote:
> > > > > John Stultz <john.stultz@...aro.org> writes:
> > > > > > From: Yu Chen <chenyu56@...wei.com>
> > > > > >
> > > > > > It needs more time for the device controller to clear the CmdAct of
> > > > > > DEPCMD on Hisilicon Kirin Soc.
> > > > >
> > > > > Why does it need more time? Why is it so that no other platform needs
> > > > > more time, only this one? And which command, specifically, causes
> > > > > problem?
> > >
> > > Sorry for my back to this so late.
> > >
> > > This change is required on my dwc3 based HW too, I gave a check
> > > and the reason is suspend_clk is used in case the PIPE phy is at P3,
> > > this slow clock makes my EP command below timeout.
> > >
> > > dwc3_gadget_ep_cmd: ep0out: cmd 'Set Endpoint Configuration' [401]
> > > params 00001000 00000500 00000000 --> status: Timed Out
> > >
> > > Success case takes about 400us to complete, see below trace(44.286278
> > > - 44.285897 = 0.000381):
> > >
> > > configfs_acm.sh-822   [000] d..1    44.285896: dwc3_writel: addr
> > > 000000006d59aae1 value 00000401
> > > configfs_acm.sh-822   [000] d..1    44.285897: dwc3_readl: addr
> > > 000000006d59aae1 value 00000401
> > > ... ...
> > > configfs_acm.sh-822   [000] d..1    44.286278: dwc3_readl: addr
> > > 000000006d59aae1 value 00000001
> > > configfs_acm.sh-822   [000] d..1    44.286279: dwc3_gadget_ep_cmd:
> > > ep0out: cmd 'Set Endpoint Configuration' [401] params 00001000
> > > 00000500 00000000 --> status: Successful
> > >
> > > Hi John,
> > >
> > > Do you still have this problem? if yes, What's the value of
> > > USBLNKST[21:18] when the timeout happens?
> >
> > Sorry. As I mentioned, I was working to upstream a patchset that I
> > hadn't created, so the context I had was limited. As I couldn't
> > reproduce an issue without the change on the device I had, I figured
> > it would be best to drop it.
>
> That was fine.
> >
> > However, as you have some analysis and rational for why such a change
> > would be needed, I don't have an objection to it. Do you want to
> > resubmit the patch with your explanation and detailed log above in the
> > commit message?
>
> Sure, I will resubmit the patch with my explanation added in commit message.

Hi John

A second think of this, I feel use readl_poll_timeout_atomic() to wait by time
is more proper here, so I create a new patch to address this also other
registers polling, see below patch with you CCed:

https://patchwork.kernel.org/patch/11536081/

thanks
Li Jun
>
> thanks
> Li Jun
> >
> > thanks
> > -john