linux-kernel - Re: [PATCH v1] usb: typec: tcpm: apply vbus before data bringup in tcpm_src

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Message-ID: <aBItn7_wakw5RqoH@kuha.fi.intel.com>
Date: Wed, 30 Apr 2025 17:03:11 +0300
From: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To: RD Babiera <rdbabiera@...gle.com>
Cc: badhri@...gle.com, gregkh@...uxfoundation.org,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Subject: Re: [PATCH v1] usb: typec: tcpm: apply vbus before data bringup in
 tcpm_src_attach

On Tue, Apr 29, 2025 at 11:47:42PM +0000, RD Babiera wrote:
> This patch fixes Type-C compliance test TD 4.7.6 - Try.SNK DRP Connect
> SNKAS.
> 
> tVbusON has a limit of 275ms when entering SRC_ATTACHED. Compliance
> testers can interpret the TryWait.Src to Attached.Src transition after
> Try.Snk as being in Attached.Src the entire time, so ~170ms is lost
> to the debounce timer.
> 
> Setting the data role can be a costly operation in host mode, and when
> completed after 100ms can cause Type-C compliance test check TD 4.7.5.V.4
> to fail.
> 
> Turn VBUS on before tcpm_set_roles to meet timing requirement.
> 
> Fixes: f0690a25a140 ("staging: typec: USB Type-C Port Manager (tcpm)")
> Cc: stable@...r.kernel.org
> Signed-off-by: RD Babiera <rdbabiera@...gle.com>
> Reviewed-by: Badhri Jagan Sridharan <badhri@...gle.com>

Reviewed-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>

> ---
>  drivers/usb/typec/tcpm/tcpm.c | 34 +++++++++++++++++-----------------
>  1 file changed, 17 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> index 784fa23102f9..e099a3c4428d 100644
> --- a/drivers/usb/typec/tcpm/tcpm.c
> +++ b/drivers/usb/typec/tcpm/tcpm.c
> @@ -4355,17 +4355,6 @@ static int tcpm_src_attach(struct tcpm_port *port)
>  
>  	tcpm_enable_auto_vbus_discharge(port, true);
>  
> -	ret = tcpm_set_roles(port, true, TYPEC_STATE_USB,
> -			     TYPEC_SOURCE, tcpm_data_role_for_source(port));
> -	if (ret < 0)
> -		return ret;
> -
> -	if (port->pd_supported) {
> -		ret = port->tcpc->set_pd_rx(port->tcpc, true);
> -		if (ret < 0)
> -			goto out_disable_mux;
> -	}
> -
>  	/*
>  	 * USB Type-C specification, version 1.2,
>  	 * chapter 4.5.2.2.8.1 (Attached.SRC Requirements)
> @@ -4375,13 +4364,24 @@ static int tcpm_src_attach(struct tcpm_port *port)
>  	    (polarity == TYPEC_POLARITY_CC2 && port->cc1 == TYPEC_CC_RA)) {
>  		ret = tcpm_set_vconn(port, true);
>  		if (ret < 0)
> -			goto out_disable_pd;
> +			return ret;
>  	}
>  
>  	ret = tcpm_set_vbus(port, true);
>  	if (ret < 0)
>  		goto out_disable_vconn;
>  
> +	ret = tcpm_set_roles(port, true, TYPEC_STATE_USB, TYPEC_SOURCE,
> +			     tcpm_data_role_for_source(port));
> +	if (ret < 0)
> +		goto out_disable_vbus;
> +
> +	if (port->pd_supported) {
> +		ret = port->tcpc->set_pd_rx(port->tcpc, true);
> +		if (ret < 0)
> +			goto out_disable_mux;
> +	}
> +
>  	port->pd_capable = false;
>  
>  	port->partner = NULL;
> @@ -4392,14 +4392,14 @@ static int tcpm_src_attach(struct tcpm_port *port)
>  
>  	return 0;
>  
> -out_disable_vconn:
> -	tcpm_set_vconn(port, false);
> -out_disable_pd:
> -	if (port->pd_supported)
> -		port->tcpc->set_pd_rx(port->tcpc, false);
>  out_disable_mux:
>  	tcpm_mux_set(port, TYPEC_STATE_SAFE, USB_ROLE_NONE,
>  		     TYPEC_ORIENTATION_NONE);
> +out_disable_vbus:
> +	tcpm_set_vbus(port, false);
> +out_disable_vconn:
> +	tcpm_set_vconn(port, false);
> +
>  	return ret;
>  }
>  
> 
> base-commit: 615dca38c2eae55aff80050275931c87a812b48c
> -- 
> 2.49.0.967.g6a0df3ecc3-goog

-- 
heikki