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

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Date:   Wed, 15 Mar 2023 10:55:20 +0800
From:   Frank Wang <frank.wang@...k-chips.com>
To:     Heikki Krogerus <heikki.krogerus@...ux.intel.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

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.

BR.
Frank