linux-kernel - Re: [PATCH 1/4] usb: typec: tcpm: fix cc role at port reset

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Message-ID: <ZBRN11OwtkvXk1Hd@kuha.fi.intel.com>
Date:   Fri, 17 Mar 2023 13:24:07 +0200
From:   Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:     Frank Wang <frank.wang@...k-chips.com>
Cc:     linux@...ck-us.net, gregkh@...uxfoundation.org, heiko@...ech.de,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-rockchip@...ts.infradead.org, huangtao@...k-chips.com,
        william.wu@...k-chips.com, jianwei.zheng@...k-chips.com,
        yubing.zhang@...k-chips.com, wmc@...k-chips.com
Subject: Re: [PATCH 1/4] usb: typec: tcpm: fix cc role at port reset

On Wed, Mar 15, 2023 at 10:55:20AM +0800, Frank Wang wrote:
> Hi Heikki,
> 
> On 2023/3/14 17:20, Heikki Krogerus wrote:
> > On Mon, Mar 13, 2023 at 10:58:40AM +0800, Frank Wang wrote:
> > > In the current implementation, the tcpm set CC1/CC2 role to open when
> > > it do port reset would cause the VBUS removed by the Type-C partner.
> > > 
> > > The Figure 4-20 in the TCPCI 2.0 specification show that the CC1/CC2
> > > role should set to 01b (Rp) or 10b (Rd) at Power On or Reset stage
> > > in DRP initialization and connection detection.
> > > 
> > > So set CC1/CC2 to Rd to fix it.
> > > 
> > > Signed-off-by: Frank Wang <frank.wang@...k-chips.com>
> > > ---
> > >   drivers/usb/typec/tcpm/tcpm.c | 2 +-
> > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> > > index a0d943d785800..66de02a56f512 100644
> > > --- a/drivers/usb/typec/tcpm/tcpm.c
> > > +++ b/drivers/usb/typec/tcpm/tcpm.c
> > > @@ -4851,7 +4851,7 @@ static void run_state_machine(struct tcpm_port *port)
> > >   		break;
> > >   	case PORT_RESET:
> > >   		tcpm_reset_port(port);
> > > -		tcpm_set_cc(port, TYPEC_CC_OPEN);
> > > +		tcpm_set_cc(port, TYPEC_CC_RD);
> > >   		tcpm_set_state(port, PORT_RESET_WAIT_OFF,
> > >   			       PD_T_ERROR_RECOVERY);
> > >   		break;
> > Will this work if the port is for example source only?
> 
> Yeah, this only set at port reset stage and CC value will be set again
> (Rd for Sink, Rp_* for Source) when start toggling.

Okay. Let's wait for comments from Guenter.

thanks,

-- 
heikki