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Sender: Guenter Roeck <groeck7@gmail.com>
Subject: Re: [PATCH v2] usb: typec: tcpm: Pass down negotiated rev to update
 retry count
To:     Badhri Jagan Sridharan <badhri@google.com>,
        Heikki Krogerus <heikki.krogerus@linux.intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20201202031733.647808-1-badhri@google.com>
From:   Guenter Roeck <linux@roeck-us.net>
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Message-ID: <6caf1208-06cb-739e-c19c-adf4a453f242@roeck-us.net>
Date:   Mon, 7 Dec 2020 13:38:36 -0800
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On 12/1/20 7:17 PM, Badhri Jagan Sridharan wrote:
> nRetryCount was updated from 3 to 2 between PD2.0 and PD3.0 spec.
> nRetryCount in "Table 6-34 Counter parameters" of the PD 2.0
> spec is set to 3, whereas, nRetryCount in "Table 6-59 Counter
> parameters" is set to 2.
> 
> Pass down negotiated rev in pd_transmit so that low level chip
> drivers can update the retry count accordingly before attempting
> packet transmission.
> 
> This helps in passing "TEST.PD.PORT.ALL.02" of the
> "Power Delivery Merged" test suite which was initially failing
> with "The UUT did not retransmit the message nReryCount times"
> 
> In fusb302 & tcpci drivers, by default the driver sets the retry
> count to 3 (Default for PD 2.0). Update this to 2,
> if the negotiated rev is PD 3.0.
> 
> In wcove, since the retry count is intentionally set to max, leaving
> it as is.
> 
> Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>

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

> ---
> Changes since V1:
> -Squashed tcpm and client patches to one as suggested by Heikki.
> ---
>  drivers/usb/typec/tcpm/fusb302.c | 16 +++++++++++-----
>  drivers/usb/typec/tcpm/tcpci.c   | 12 +++++++-----
>  drivers/usb/typec/tcpm/tcpm.c    |  2 +-
>  drivers/usb/typec/tcpm/wcove.c   |  3 ++-
>  include/linux/usb/tcpm.h         |  2 +-
>  5 files changed, 22 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/usb/typec/tcpm/fusb302.c b/drivers/usb/typec/tcpm/fusb302.c
> index 99562cc65ca6..ebc46b9f776c 100644
> --- a/drivers/usb/typec/tcpm/fusb302.c
> +++ b/drivers/usb/typec/tcpm/fusb302.c
> @@ -343,12 +343,11 @@ static int fusb302_sw_reset(struct fusb302_chip *chip)
>  	return ret;
>  }
>  
> -static int fusb302_enable_tx_auto_retries(struct fusb302_chip *chip)
> +static int fusb302_enable_tx_auto_retries(struct fusb302_chip *chip, u8 retry_count)
>  {
>  	int ret = 0;
>  
> -	ret = fusb302_i2c_set_bits(chip, FUSB_REG_CONTROL3,
> -				   FUSB_REG_CONTROL3_N_RETRIES_3 |
> +	ret = fusb302_i2c_set_bits(chip, FUSB_REG_CONTROL3, retry_count |
>  				   FUSB_REG_CONTROL3_AUTO_RETRY);
>  
>  	return ret;
> @@ -399,7 +398,7 @@ static int tcpm_init(struct tcpc_dev *dev)
>  	ret = fusb302_sw_reset(chip);
>  	if (ret < 0)
>  		return ret;
> -	ret = fusb302_enable_tx_auto_retries(chip);
> +	ret = fusb302_enable_tx_auto_retries(chip, FUSB_REG_CONTROL3_N_RETRIES_3);
>  	if (ret < 0)
>  		return ret;
>  	ret = fusb302_init_interrupt(chip);
> @@ -1017,7 +1016,7 @@ static const char * const transmit_type_name[] = {
>  };
>  
>  static int tcpm_pd_transmit(struct tcpc_dev *dev, enum tcpm_transmit_type type,
> -			    const struct pd_message *msg)
> +			    const struct pd_message *msg, unsigned int negotiated_rev)
>  {
>  	struct fusb302_chip *chip = container_of(dev, struct fusb302_chip,
>  						 tcpc_dev);
> @@ -1026,6 +1025,13 @@ static int tcpm_pd_transmit(struct tcpc_dev *dev, enum tcpm_transmit_type type,
>  	mutex_lock(&chip->lock);
>  	switch (type) {
>  	case TCPC_TX_SOP:
> +		/* nRetryCount 3 in P2.0 spec, whereas 2 in PD3.0 spec */
> +		ret = fusb302_enable_tx_auto_retries(chip, negotiated_rev > PD_REV20 ?
> +						     FUSB_REG_CONTROL3_N_RETRIES_2 :
> +						     FUSB_REG_CONTROL3_N_RETRIES_3);
> +		if (ret < 0)
> +			fusb302_log(chip, "Cannot update retry count ret=%d", ret);
> +
>  		ret = fusb302_pd_send_message(chip, msg);
>  		if (ret < 0)
>  			fusb302_log(chip,
> diff --git a/drivers/usb/typec/tcpm/tcpci.c b/drivers/usb/typec/tcpm/tcpci.c
> index 12d983a75510..98a2455f779f 100644
> --- a/drivers/usb/typec/tcpm/tcpci.c
> +++ b/drivers/usb/typec/tcpm/tcpci.c
> @@ -18,7 +18,8 @@
>  
>  #include "tcpci.h"
>  
> -#define	PD_RETRY_COUNT				3
> +#define	PD_RETRY_COUNT_DEFAULT			3
> +#define	PD_RETRY_COUNT_3_0_OR_HIGHER		2
>  #define	AUTO_DISCHARGE_DEFAULT_THRESHOLD_MV	3500
>  #define	AUTO_DISCHARGE_PD_HEADROOM_MV		850
>  #define	AUTO_DISCHARGE_PPS_HEADROOM_MV		1250
> @@ -447,9 +448,8 @@ static int tcpci_set_vbus(struct tcpc_dev *tcpc, bool source, bool sink)
>  	return 0;
>  }
>  
> -static int tcpci_pd_transmit(struct tcpc_dev *tcpc,
> -			     enum tcpm_transmit_type type,
> -			     const struct pd_message *msg)
> +static int tcpci_pd_transmit(struct tcpc_dev *tcpc, enum tcpm_transmit_type type,
> +			     const struct pd_message *msg, unsigned int negotiated_rev)
>  {
>  	struct tcpci *tcpci = tcpc_to_tcpci(tcpc);
>  	u16 header = msg ? le16_to_cpu(msg->header) : 0;
> @@ -497,7 +497,9 @@ static int tcpci_pd_transmit(struct tcpc_dev *tcpc,
>  		}
>  	}
>  
> -	reg = (PD_RETRY_COUNT << TCPC_TRANSMIT_RETRY_SHIFT) | (type << TCPC_TRANSMIT_TYPE_SHIFT);
> +	/* nRetryCount is 3 in PD2.0 spec where 2 in PD3.0 spec */
> +	reg = ((negotiated_rev > PD_REV20 ? PD_RETRY_COUNT_3_0_OR_HIGHER : PD_RETRY_COUNT_DEFAULT)
> +	       << TCPC_TRANSMIT_RETRY_SHIFT) | (type << TCPC_TRANSMIT_TYPE_SHIFT);
>  	ret = regmap_write(tcpci->regmap, TCPC_TRANSMIT, reg);
>  	if (ret < 0)
>  		return ret;
> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> index 3bbc1f10af49..c73bc3a8356a 100644
> --- a/drivers/usb/typec/tcpm/tcpm.c
> +++ b/drivers/usb/typec/tcpm/tcpm.c
> @@ -667,7 +667,7 @@ static int tcpm_pd_transmit(struct tcpm_port *port,
>  		tcpm_log(port, "PD TX, type: %#x", type);
>  
>  	reinit_completion(&port->tx_complete);
> -	ret = port->tcpc->pd_transmit(port->tcpc, type, msg);
> +	ret = port->tcpc->pd_transmit(port->tcpc, type, msg, port->negotiated_rev);
>  	if (ret < 0)
>  		return ret;
>  
> diff --git a/drivers/usb/typec/tcpm/wcove.c b/drivers/usb/typec/tcpm/wcove.c
> index 9b745f432c91..79ae63950050 100644
> --- a/drivers/usb/typec/tcpm/wcove.c
> +++ b/drivers/usb/typec/tcpm/wcove.c
> @@ -356,7 +356,8 @@ static int wcove_set_pd_rx(struct tcpc_dev *tcpc, bool on)
>  
>  static int wcove_pd_transmit(struct tcpc_dev *tcpc,
>  			     enum tcpm_transmit_type type,
> -			     const struct pd_message *msg)
> +			     const struct pd_message *msg,
> +			     unsigned int negotiated_rev)
>  {
>  	struct wcove_typec *wcove = tcpc_to_wcove(tcpc);
>  	unsigned int info = 0;
> diff --git a/include/linux/usb/tcpm.h b/include/linux/usb/tcpm.h
> index e68aaa12886f..efaedd7e8a18 100644
> --- a/include/linux/usb/tcpm.h
> +++ b/include/linux/usb/tcpm.h
> @@ -121,7 +121,7 @@ struct tcpc_dev {
>  			      enum typec_cc_status cc);
>  	int (*try_role)(struct tcpc_dev *dev, int role);
>  	int (*pd_transmit)(struct tcpc_dev *dev, enum tcpm_transmit_type type,
> -			   const struct pd_message *msg);
> +			   const struct pd_message *msg, unsigned int negotiated_rev);
>  	int (*set_bist_data)(struct tcpc_dev *dev, bool on);
>  	int (*enable_frs)(struct tcpc_dev *dev, bool enable);
>  	void (*frs_sourcing_vbus)(struct tcpc_dev *dev);
>