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Date:   Fri, 16 Mar 2018 14:32:06 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Hans de Goede <hdegoede@...hat.com>, Jun Li <jun.li@....com>,
        "Regupathy, Rajaram" <rajaram.regupathy@...el.com>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH v2 3/3] usb: typec: tcpm: Support for Alternate Modes

On Fri, Mar 09, 2018 at 06:19:18PM +0300, Heikki Krogerus wrote:
> This adds more complete handling of VDMs and registration of
> partner alternate modes, and introduces callbacks for
> alternate mode operations.
> 
> Only DFP role is supported for now.
> 
> Signed-off-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> ---
>  drivers/usb/typec/tcpm.c | 133 +++++++++++++++++++++++++++++++++++++++--------
>  1 file changed, 111 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/usb/typec/tcpm.c b/drivers/usb/typec/tcpm.c
> index bfb843ebffa6..34bf5c1f4d81 100644
> --- a/drivers/usb/typec/tcpm.c
> +++ b/drivers/usb/typec/tcpm.c
> @@ -158,13 +158,14 @@ enum pd_msg_request {
>  /* Alternate mode support */
>  
>  #define SVID_DISCOVERY_MAX	16
> +#define ALTMODE_DISCOVERY_MAX	(SVID_DISCOVERY_MAX * MODE_DISCOVERY_MAX)
>  
>  struct pd_mode_data {
>  	int svid_index;		/* current SVID index		*/
>  	int nsvids;
>  	u16 svids[SVID_DISCOVERY_MAX];
>  	int altmodes;		/* number of alternate modes	*/
> -	struct typec_altmode_desc altmode_desc[SVID_DISCOVERY_MAX];
> +	struct typec_altmode_desc altmode_desc[ALTMODE_DISCOVERY_MAX];
>  };
>  
>  struct tcpm_port {
> @@ -280,8 +281,8 @@ struct tcpm_port {
>  	/* Alternate mode data */
>  
>  	struct pd_mode_data mode_data;
> -	struct typec_altmode *partner_altmode[SVID_DISCOVERY_MAX * 6];
> -	struct typec_altmode *port_altmode[SVID_DISCOVERY_MAX * 6];
> +	struct typec_altmode *partner_altmode[ALTMODE_DISCOVERY_MAX];
> +	struct typec_altmode *port_altmode[ALTMODE_DISCOVERY_MAX];
>  
>  	/* Deadline in jiffies to exit src_try_wait state */
>  	unsigned long max_wait;
> @@ -985,36 +986,53 @@ static void svdm_consume_modes(struct tcpm_port *port, const __le32 *payload,
>  			 pmdata->altmodes, paltmode->svid,
>  			 paltmode->mode, paltmode->vdo);
>  
> -		port->partner_altmode[pmdata->altmodes] =
> -			typec_partner_register_altmode(port->partner, paltmode);
> -		if (!port->partner_altmode[pmdata->altmodes]) {
> -			tcpm_log(port,
> -				 "Failed to register modes for SVID 0x%04x",
> -				 paltmode->svid);
> -			return;
> -		}
>  		pmdata->altmodes++;
>  	}
>  }
>  
> +static void tcpm_register_partner_altmodes(struct tcpm_port *port)
> +{
> +	struct pd_mode_data *modep = &port->mode_data;
> +	struct typec_altmode *altmode;
> +	int i;
> +
> +	for (i = 0; i < modep->altmodes; i++) {
> +		altmode = typec_partner_register_altmode(port->partner,
> +						&modep->altmode_desc[i]);
> +		if (!altmode)
> +			tcpm_log(port, "Failed to register partner SVID 0x%04x",
> +				 modep->altmode_desc[i].svid);
> +		port->partner_altmode[i] = altmode;
> +	}
> +}
> +
>  #define supports_modal(port)	PD_IDH_MODAL_SUPP((port)->partner_ident.id_header)
>  
>  static int tcpm_pd_svdm(struct tcpm_port *port, const __le32 *payload, int cnt,
>  			u32 *response)
>  {
> -	u32 p0 = le32_to_cpu(payload[0]);
> -	int cmd_type = PD_VDO_CMDT(p0);
> -	int cmd = PD_VDO_CMD(p0);
> +	struct typec_altmode *altmode;
>  	struct pd_mode_data *modep;
> +	u32 p[PD_MAX_PAYLOAD];
>  	int rlen = 0;
> -	u16 svid;
> +	int cmd_type;
> +	int cmd;
>  	int i;
>  
> +	for (i = 0; i < cnt; i++)
> +		p[i] = le32_to_cpu(payload[i]);
> +
> +	cmd_type = PD_VDO_CMDT(p[0]);
> +	cmd = PD_VDO_CMD(p[0]);
> +
>  	tcpm_log(port, "Rx VDM cmd 0x%x type %d cmd %d len %d",
> -		 p0, cmd_type, cmd, cnt);
> +		 p[0], cmd_type, cmd, cnt);
>  
>  	modep = &port->mode_data;
>  
> +	altmode = typec_match_altmode(port->port_altmode, ALTMODE_DISCOVERY_MAX,
> +				      PD_VDO_VID(p[0]), PD_VDO_OPOS(p[0]));

This can return NULL ...

> +
>  	switch (cmd_type) {
>  	case CMDT_INIT:
>  		switch (cmd) {
> @@ -1036,17 +1054,21 @@ static int tcpm_pd_svdm(struct tcpm_port *port, const __le32 *payload, int cnt,
>  		case CMD_EXIT_MODE:
>  			break;
>  		case CMD_ATTENTION:
> -			break;
> +			typec_altmode_attention(altmode, p[1]);

... and NULL is not handled by typec_altmode_attention().

> +			return 0;
>  		default:
> +			if (typec_altmode_vdm(altmode, p[0], &p[1], cnt) ==
> +			    VDM_OK)

typec_altmode_vdm() returns old fashioned error messages.
Not sure what it is supposed to return, though.

> +				return 0;
>  			break;
>  		}
>  		if (rlen >= 1) {
> -			response[0] = p0 | VDO_CMDT(CMDT_RSP_ACK);
> +			response[0] = p[0] | VDO_CMDT(CMDT_RSP_ACK);
>  		} else if (rlen == 0) {
> -			response[0] = p0 | VDO_CMDT(CMDT_RSP_NAK);
> +			response[0] = p[0] | VDO_CMDT(CMDT_RSP_NAK);
>  			rlen = 1;
>  		} else {
> -			response[0] = p0 | VDO_CMDT(CMDT_RSP_BUSY);
> +			response[0] = p[0] | VDO_CMDT(CMDT_RSP_BUSY);
>  			rlen = 1;
>  		}
>  		break;
> @@ -1079,20 +1101,26 @@ static int tcpm_pd_svdm(struct tcpm_port *port, const __le32 *payload, int cnt,
>  			svdm_consume_modes(port, payload, cnt);
>  			modep->svid_index++;
>  			if (modep->svid_index < modep->nsvids) {
> -				svid = modep->svids[modep->svid_index];
> +				u16 svid = modep->svids[modep->svid_index];
>  				response[0] = VDO(svid, 1, CMD_DISCOVER_MODES);
>  				rlen = 1;
>  			} else {
> -				/* enter alternate mode if/when implemented */
> +				tcpm_register_partner_altmodes(port);
>  			}
>  			break;
>  		case CMD_ENTER_MODE:
> +			typec_altmode_enter(altmode);

typec_altmode_enter() don't handle altmode == NULL.
No error handling ?

> +			break;
> +		case CMD_EXIT_MODE:
> +			typec_altmode_exit(altmode);

Doesn't handle NULL. Error handling ?

>  			break;
>  		default:
> +			typec_altmode_vdm(altmode, p[0], &p[1], cnt);
>  			break;
>  		}
>  		break;
>  	default:
> +		typec_altmode_vdm(altmode, p[0], &p[1], cnt);
>  		break;
>  	}
>  
> @@ -1352,6 +1380,47 @@ static int tcpm_validate_caps(struct tcpm_port *port, const u32 *pdo,
>  	return 0;
>  }
>  
> +static void tcpm_altmode_enter(struct typec_altmode *altmode)
> +{
> +	struct tcpm_port *port = typec_altmode_get_drvdata(altmode);
> +	u32 header;
> +
> +	header = VDO(altmode->svid, 1, CMD_ENTER_MODE);
> +	header |= VDO_OPOS(altmode->mode);
> +
> +	tcpm_queue_vdm(port, header, NULL, 0);
> +	mod_delayed_work(port->wq, &port->vdm_state_machine, 0);
> +}
> +
> +static void tcpm_altmode_exit(struct typec_altmode *altmode)
> +{
> +	struct tcpm_port *port = typec_altmode_get_drvdata(altmode);
> +	u32 header;
> +
> +	header = VDO(altmode->svid, 1, CMD_EXIT_MODE);
> +	header |= VDO_OPOS(altmode->mode);
> +
> +	tcpm_queue_vdm(port, header, NULL, 0);
> +	mod_delayed_work(port->wq, &port->vdm_state_machine, 0);
> +}
> +
> +static int tcpm_altmode_vdm(struct typec_altmode *altmode,
> +			    u32 header, const u32 *data, int count)
> +{
> +	struct tcpm_port *port = typec_altmode_get_drvdata(altmode);
> +
> +	tcpm_queue_vdm(port, header, data, count - 1);
> +	mod_delayed_work(port->wq, &port->vdm_state_machine, 0);
> +
> +	return 0;
> +}
> +
> +static const struct typec_altmode_ops tcpm_altmode_ops = {
> +	.enter = tcpm_altmode_enter,
> +	.exit = tcpm_altmode_exit,
> +	.vdm = tcpm_altmode_vdm,
> +};
> +
>  /*
>   * PD (data, control) command handling functions
>   */
> @@ -3479,6 +3548,23 @@ static void tcpm_init(struct tcpm_port *port)
>  	tcpm_set_state(port, PORT_RESET, 0);
>  }
>  
> +static int tcpm_activate_mode(struct typec_altmode *alt, int activate)
> +{
> +	struct tcpm_port *port = typec_altmode_get_drvdata(alt);
> +	u32 header;
> +
> +	header = VDO(cpu_to_le16(alt->svid), 1,
> +		     activate ? CMD_ENTER_MODE : CMD_EXIT_MODE);
> +	header |= VDO_OPOS(alt->mode);
> +
> +	mutex_lock(&port->lock);
> +	tcpm_queue_vdm(port, header, NULL, 0);
> +	mod_delayed_work(port->wq, &port->vdm_state_machine, 0);
> +	mutex_unlock(&port->lock);

Some of the above functions are port mutex protected, some are not.
Is this on purpose ?

> +
> +	return 0;
> +}
> +
>  static int tcpm_port_type_set(const struct typec_capability *cap,
>  			      enum typec_port_type type)
>  {
> @@ -3671,6 +3757,7 @@ struct tcpm_port *tcpm_register_port(struct device *dev, struct tcpc_dev *tcpc)
>  	port->typec_caps.pr_set = tcpm_pr_set;
>  	port->typec_caps.vconn_set = tcpm_vconn_set;
>  	port->typec_caps.try_role = tcpm_try_role;
> +	port->typec_caps.activate_mode = tcpm_activate_mode;
>  	port->typec_caps.port_type_set = tcpm_port_type_set;
>  
>  	port->partner_desc.identity = &port->partner_ident;
> @@ -3703,6 +3790,8 @@ struct tcpm_port *tcpm_register_port(struct device *dev, struct tcpc_dev *tcpc)
>  					 dev_name(dev), paltmode->svid);
>  				break;
>  			}
> +			typec_altmode_set_drvdata(alt, port);
> +			typec_altmode_register_ops(alt, &tcpm_altmode_ops);
>  			port->port_altmode[i] = alt;
>  			i++;
>  			paltmode++;
> -- 
> 2.16.1
> 

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