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

From: Jun Li <lijun.kernel@gmail.com>
To: John Stultz <john.stultz@linaro.org>
Cc: Felipe Balbi <balbi@kernel.org>,
	lkml <linux-kernel@vger.kernel.org>,
	Yu Chen <chenyu56@huawei.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	ShuFan Lee <shufan_lee@richtek.com>,
	Heikki Krogerus <heikki.krogerus@linux.intel.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Chunfeng Yun <chunfeng.yun@mediatek.com>,
	Hans de Goede <hdegoede@redhat.com>,
	Andy Shevchenko <andy.shevchenko@gmail.com>,
	Valentin Schneider <valentin.schneider@arm.com>,
	Jack Pham <jackp@codeaurora.org>,
	Linux USB List <linux-usb@vger.kernel.org>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@vger.kernel.org>
Subject: Re: [PATCH v4 3/9] usb: dwc3: Increase timeout for CmdAct cleared by device controller
Date: Wed, 6 May 2020 17:00:20 +0800	[thread overview]
Message-ID: <CAKgpwJVaKpsgMjKcnYyJsfNj0ibkPt=mdn-NxfOkeX1jfL=9iQ@mail.gmail.com> (raw)
In-Reply-To: <CALAqxLU+9uEcdRVaLfh+eQrDtZbDGod9pRXhBX=prAhg9MXagw@mail.gmail.com>

John Stultz <john.stultz@linaro.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@kernel.org> wrote:
> > John Stultz <john.stultz@linaro.org> writes:
> > > From: Yu Chen <chenyu56@huawei.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?

thanks
Li Jun
>
> Hrm. Sadly I don't have that context (again I'm picking up a
> semi-abandoned patchset here), which is unfortunate, as I'm sure
> someone spent a number of hours debugging things to come up with this.
> :)
>
> But alas, I've dropped this for now in my stack, and things seem to be
> working ok so far. I suspect there's some edge case I'll run into, but
> hopefully I'll be able to debug and get more details when that
> happens.
>
> I do appreciate the review and pushback here!
>
> thanks
> -john