linux-kernel - Re: [PATCH 3/3 v3] usb: typec: tcpm: Stay in BIST mode till hardreset or unattached

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Date:   Wed, 15 Jul 2020 21:16:59 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Badhri Jagan Sridharan <badhri@...gle.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        reg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3 v3] usb: typec: tcpm: Stay in BIST mode till hardreset
 or unattached

On 7/15/20 8:41 PM, Badhri Jagan Sridharan wrote:
> Port starts to toggle when transitioning to unattached state.
> This is incorrect while in BIST mode.
> 
> 6.4.3.1 BIST Carrier Mode
> Upon receipt of a BIST Message, with a BIST Carrier Mode BIST Data Object,
> the UUT Shall send out a continuous string of BMC encoded alternating "1"s
> and “0”s. The UUT Shall exit the Continuous BIST Mode within
> tBISTContMode of this Continuous BIST Mode being enabled(see
> Section 6.6.7.2).
> 
> 6.4.3.2 BIST Test Data
> Upon receipt of a BIST Message, with a BIST Test Data BIST Data Object,
> the UUT Shall return a GoodCRC Message and Shall enter a test mode in which
> it sends no further Messages except for GoodCRC Messages in response to
> received Messages. See Section 5.9.2 for the definition of the Test Data
> Frame. The test Shall be ended by sending Hard Reset Signaling to reset the
> UUT.
> 
> Signed-off-by: Badhri Jagan Sridharan <badhri@...gle.com>

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

> ---
> Version history:
> Changes since V1:
> - None
> 
> Changes since V2:(Guenter's suggestions)
> - Fixed formatting error
> - Reduced timeout to 50ms
> 
> ---
>  drivers/usb/typec/tcpm/tcpm.c | 7 +++++--
>  include/linux/usb/pd.h        | 1 +
>  2 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> index 379fcab9dbd973..38b958a9650104 100644
> --- a/drivers/usb/typec/tcpm/tcpm.c
> +++ b/drivers/usb/typec/tcpm/tcpm.c
> @@ -3559,6 +3559,8 @@ static void run_state_machine(struct tcpm_port *port)
>  		switch (BDO_MODE_MASK(port->bist_request)) {
>  		case BDO_MODE_CARRIER2:
>  			tcpm_pd_transmit(port, TCPC_TX_BIST_MODE_2, NULL);
> +			tcpm_set_state(port, unattached_state(port),
> +				       PD_T_BIST_CONT_MODE);
>  			break;
>  		case BDO_MODE_TESTDATA:
>  			if (port->tcpc->set_bist_data) {
> @@ -3569,8 +3571,6 @@ static void run_state_machine(struct tcpm_port *port)
>  		default:
>  			break;
>  		}
> -		/* Always switch to unattached state */
> -		tcpm_set_state(port, unattached_state(port), 0);
>  		break;
>  	case GET_STATUS_SEND:
>  		tcpm_pd_send_control(port, PD_CTRL_GET_STATUS);
> @@ -3960,6 +3960,9 @@ static void _tcpm_pd_vbus_off(struct tcpm_port *port)
>  static void _tcpm_pd_hard_reset(struct tcpm_port *port)
>  {
>  	tcpm_log_force(port, "Received hard reset");
> +	if (port->bist_request == BDO_MODE_TESTDATA && port->tcpc->set_bist_data)
> +		port->tcpc->set_bist_data(port->tcpc, false);
> +
>  	/*
>  	 * If we keep receiving hard reset requests, executing the hard reset
>  	 * must have failed. Revert to error recovery if that happens.
> diff --git a/include/linux/usb/pd.h b/include/linux/usb/pd.h
> index a665d7f211424d..b6c233e79bd457 100644
> --- a/include/linux/usb/pd.h
> +++ b/include/linux/usb/pd.h
> @@ -483,4 +483,5 @@ static inline unsigned int rdo_max_power(u32 rdo)
>  #define PD_N_CAPS_COUNT		(PD_T_NO_RESPONSE / PD_T_SEND_SOURCE_CAP)
>  #define PD_N_HARD_RESET_COUNT	2
>  
> +#define PD_T_BIST_CONT_MODE	50 /* 30 - 60 ms */
>  #endif /* __LINUX_USB_PD_H */
>