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Message-ID: <CADiBU38-jX=4sbQ9aFoA=Xr6S7cFbfQy8tpdohoZdpaY-AK-Vw@mail.gmail.com>
Date: Sat, 10 Oct 2020 00:06:13 +0800
From: ChiYuan Huang <u0084500@...il.com>
To: Jun Li <jun.li@....com>
Cc: Jun Li <lijun.kernel@...il.com>,
Guenter Roeck <linux@...ck-us.net>,
Greg KH <gregkh@...uxfoundation.org>,
Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
Linux USB List <linux-usb@...r.kernel.org>,
lkml <linux-kernel@...r.kernel.org>,
cy_huang <cy_huang@...htek.com>
Subject: Re: [PATCH] usb: typec: tcpm: Fix if vbus before cc, hard_reset_count
not reset issue
Jun Li <jun.li@....com> 於 2020年10月9日 週五 下午2:12寫道：
>
>
>
> > -----Original Message-----
> > From: ChiYuan Huang <u0084500@...il.com>
> > Sent: Wednesday, October 7, 2020 6:13 PM
> > To: Jun Li <lijun.kernel@...il.com>
> > Cc: Guenter Roeck <linux@...ck-us.net>; Greg KH
> > <gregkh@...uxfoundation.org>; Heikki Krogerus
> > <heikki.krogerus@...ux.intel.com>; Linux USB List
> > <linux-usb@...r.kernel.org>; lkml <linux-kernel@...r.kernel.org>;
> > cy_huang <cy_huang@...htek.com>; Jun Li <jun.li@....com>
> > Subject: Re: [PATCH] usb: typec: tcpm: Fix if vbus before cc, hard_reset_count
> > not reset issue
> >
> > ChiYuan Huang <u0084500@...il.com> 於 2020年10月7日 週三 上午1:39寫道：
> > >
> > > Jun Li <lijun.kernel@...il.com> 於 2020年10月7日 週三 上午12:52寫道：
> > > >
> > > > ChiYuan Huang <u0084500@...il.com> 于2020年10月6日周二 下午12:38写
> > 道：
> > > > >
> > > > > Guenter Roeck <linux@...ck-us.net> 於 2020年10月5日 週一 下午11:30
> > 寫道：
> > > > > >
> > > > > > On 10/5/20 4:08 AM, Greg KH wrote:
> > > > > > [ ... ]
> > > > > > >>> What ever happened with this patch, is there still disagreement?
> > > > > > >>>
> > > > > > >>
> > > > > > >> Yes, there is. I wouldn't have added the conditional without
> > > > > > >> reason, and I am concerned that removing it entirely will open
> > another problem.
> > > > > > >> Feel free to apply, though - I can't prove that my concern is
> > > > > > >> valid, and after all we'll get reports from the field later if
> > it is.
> > > > > > >
> > > > > > > Ok, can I get an ack so I know who to come back to in the
> > > > > > > future if there are issues? :)
> > > > > > >
> > > > > >
> > > > > > Not from me, for the reasons I stated. I would be ok with something
> > like:
> > > > > >
> > > > > > - if (tcpm_port_is_disconnected(port))
> > > > > > + if (tcpm_port_is_disconnected(port) ||
> > > > > > + (tcpm_cc_is_open(port->cc1) &&
> > > > > > + tcpm_cc_is_open(port->cc2)))
> > > > > >
> > > > > > to narrow down the condition.
> > > > >
> > > > > I have tried the above comment and It doesn't work.
> > > > > How about to change the judgement like as below
> > > > >
> > > > > - if (tcpm_port_is_disconnected(port))
> > > > > + if (tcpm_port_is_disconnected(port) ||
> > > > > + !port->vbus_present)
> > > > >
> > > > > The hard_reset_count not reset issue is following by the below
> > > > > order 1. VBUS off ( at the same time, cc is still detected as
> > > > > attached)
> > > > > port->attached become false and cc is not open
> > > > > 2. After that, cc detached.
> > > > > due to port->attached is false, tcpm_detach() directly return.
> > > >
> > > > If tcpm_detach() return directly, then how your patch can reset
> > > > hard_reset_count?
> > > >
> > > Yes, it can. We know vbus_present change from true to false and cc
> > > detach both trigger tcpm_detach.
> > > My change is whenever tcpm_detach to be called, hard_reset_count will
> > > be reset to zero.
> > >
> > > > I am seeing the same issue on my platform, the proposed change:
> > > > - if (tcpm_port_is_disconnected(port))
> > > > - port->hard_reset_count = 0;
> > > > + port->hard_reset_count = 0;
> > > > can't resolve it on my platform.
> > > >
> > > I'm not sure what's your condition. Could you directly paste the tcpm
> > > log for the check?
> > > > How about reset hard_reset_count in SNK_READY?
> > > > @@ -3325,6 +3329,7 @@ static void run_state_machine(struct tcpm_port
> > *port)
> > > > case SNK_READY:
> > > > port->try_snk_count = 0;
> > > > port->update_sink_caps = false;
> > > > + port->hard_reset_count = 0;
> > > > if (port->explicit_contract) {
> > > > typec_set_pwr_opmode(port->typec_port,
> > > > TYPEC_PWR_MODE_PD);
> > > >
> > > > can this resolve your problem?
> > > I'm not sure. It need to have a try, then I can answer you.
> > > But from USBPD spec, the hard_reset_count need to reset zero only when
> > > 1. At src state, pe_src_send_cap and receive GoodCRC 2. At snk state,
> > > pe_snk_evaluate_cap need to reset hard_reset_count
>
> 3.
> 8.3.3.3.8 PE_SNK_Hard_Reset state
> "Note: The HardResetCounter is reset on a power cycle or Detach."
>
> > > >
> > > > Li Jun
> > > > >
> > > > > And that's why hard_reset_count is not reset to 0.
> >
> > I tried in snk_ready to reset hard_reset_count.
> > At normal case, it works.
> > But it seems still the possible fail case like as below.
> > 200ms -> cc debounce max time
> > 240ms -> snk_waitcap max time
> > If the plugin/out period is between (200+240) and (200+ 2* 240)ms , and the
> > src side plug out like as the described scenario.
> > From this case, hard_reset_count may still 1.
> > And we expect the next plugin hard_reset_count is 0. But not, actually it
> > never reset.
> > So at next plugin, only one hard_reset will be sent and reach hard_reset_count
> > max (2).
> >
> > This case is hard to reproduce. But actually it's possible.
>
> Make sense.
>
> Then I propose doing this at SNK_UNATTACHED
> @@ -3156,6 +3156,7 @@ static void run_state_machine(struct tcpm_port *port)
> if (!port->non_pd_role_swap)
> tcpm_swap_complete(port, -ENOTCONN);
> tcpm_pps_complete(port, -ENOTCONN);
> + port->hard_reset_count = 0;
> tcpm_snk_detach(port);
> if (tcpm_start_toggling(port, TYPEC_CC_RD)) {
> tcpm_set_state(port, TOGGLING, 0);
> Li Jun
For the current power role is snk, I think it may work.
How about the src role? src role only reset the hard_reset_count in
tcpm_detach and src_ready state?
I check the flow that you mentioned in the previous mail. It's really
a special case from any state to port_reset.
If the case is considered, how about to reset the hard_reset_count
and don't care the port is attached or not in tcpm_detach function
like as below.
@@ -2789,6 +2789,8 @@ static void tcpm_reset_port(struct tcpm_port *port)
static void tcpm_detach(struct tcpm_port *port)
{
+ port->hard_reset_count = 0;
+
if (!port->attached)
return;
@@ -2797,9 +2799,6 @@ static void tcpm_detach(struct tcpm_port *port)
port->tcpc->set_bist_data(port->tcpc, false);
}
- if (tcpm_port_is_disconnected(port))
- port->hard_reset_count = 0;
-
tcpm_reset_port(port);
}
Like I mentioned before, whatever the condition is, hard_reset_count
must be reset to zero during tcpm_detach.
But refer to Guenter's mail, he prefer to narrow down the condition
to reset this counter.
I think the original thought is important why to put this line there.
Hi, Guenter:
From the discussion, we really need to know why you put the reset
line below port attached is false and also make some judgement.
I think there may be ome condition that we don't considered.
>
> >
> > > > > >
> > > > > > Guenter
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