From: Jeaho Hwang <jhhwang@rtst.co.kr>
To: Peter Chen <peter.chen@kernel.org>
Cc: "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
"Linux team" <team-linux@rtst.co.kr>,
"변무광(Byeon Moo Kwang)/자동화연)Automation Platform연구팀"
<mkbyeon@lselectric.co.kr>,
"최기홍(Choi Ki Hong)/자동화연)Automation Platform연구팀"
<khchoib@lselectric.co.kr>
Subject: Re: [PATCH v2] usb: chipidea: add loop timeout for hw_ep_set_halt()
Date: Fri, 27 Aug 2021 10:35:05 +0900 [thread overview]
Message-ID: <CAJk_X9i68vPWDEf2x6WtV73XRCuhyZF_26KtK=J+Z76ZyQe8PQ@mail.gmail.com> (raw)
In-Reply-To: <20210826230658.GB4335@Peter>
2021년 8월 27일 (금) 오전 8:08, Peter Chen <peter.chen@kernel.org>님이 작성:
>
> On 21-08-24 17:31:44, Jeaho Hwang wrote:
> > 2021년 8월 17일 (화) 오후 3:44, Jeaho Hwang <jhhwang@rtst.co.kr>님이 작성:
> > >
> > > If ctrl EP priming is failed (very rare case in standard linux),
> > > hw_ep_set_halt goes infinite loop. waiting 100 times was enough
> > > for zynq7000.
> > >
> >
> > Hi Peter.
> > I found from zynq7000 TRM that the hardware clears Stall bit if a
> > setup packet is received on a control endpoint.
> > I think hw_ep_set_halt goes infinite loop since:
> >
> > 1. hw_ep_prime for control EP which is called from
> > isr_tr_complete_handler -> isr_setup_status_phase is failed due to a
> > setup packet received.
>
> How do you know that? Do you observe the new setup packet on the bus
> before the current status stage? Usually, the host doesn't begin new setup
> transfer before current setup transfer has finished.
>
> Peter
>
I found an error return from the second ENDPTSETUPSTAT checking
routine, then setting the stall bit(TXS) kept failing. So I guessed it
is due to a setup packet received.
I didn't observe the setup packet by e.g. HW probes. Any other reason
to produce that symptom?
For reminder, only reproduced on preemp_rt kernel and with Windows(10)
RNDIS host.
thanks.
191 static int hw_ep_prime(struct ci_hdrc *ci, int num, int dir, int is_ctrl)
192 {
193 int n = hw_ep_bit(num, dir);
194
195 /* Synchronize before ep prime */
196 wmb();
197
198 if (is_ctrl && dir == RX && hw_read(ci, OP_ENDPTSETUPSTAT, BIT(num)))
199 return -EAGAIN;
200
201 hw_write(ci, OP_ENDPTPRIME, ~0, BIT(n));
202
203 while (hw_read(ci, OP_ENDPTPRIME, BIT(n)))
204 cpu_relax();
205 if (is_ctrl && dir == RX && hw_read(ci, OP_ENDPTSETUPSTAT, BIT(num)))
206 return -EAGAIN;
~~~~~~~~~~~~~~~~
207
208 /* status shoult be tested according with manual but it doesn't work */
209 return 0;
210 }
> > 2. in isr_tr_complete_handler it tries to call _ep_set_halt if either
> > isr_tr_complete_low or isr_setup_status_phase returns error.
> > 3. Since the control EP got a setup packet, HW resets TXS bit just as
> > the driver sets inside hw_ep_set_halt so it goes infinite loop.
> >
> > Does it make sense? If it is right, we shouldn't call _ep_set_halt if
> > the err is -EAGAIN, which could be returned ONLY due to the setup
> > packet issue described above.
> > And the loop timeout is not required anymore.
> >
> > Can I ask your opinion on this, Peter and USB experts?
> >
> > Thanks.
> >
next prev parent reply other threads:[~2021-08-27 1:35 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-17 6:43 [PATCH v2] usb: chipidea: add loop timeout for hw_ep_set_halt() Jeaho Hwang
2021-08-24 8:31 ` Jeaho Hwang
2021-08-26 23:07 ` Peter Chen
2021-08-27 1:35 ` Jeaho Hwang [this message]
2021-08-28 1:38 ` Peter Chen
2021-08-28 3:10 ` Jeaho Hwang
2021-08-26 11:17 ` Greg Kroah-Hartman
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