linux-kernel - Re: [PATCH v9 2/3] usb: typec: tcpci: Add callback for evaluating contaminant presence

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Date:   Sat, 10 Dec 2022 08:07:58 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Badhri Jagan Sridharan <badhri@...gle.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kyle Tso <kyletso@...gle.com>
Subject: Re: [PATCH v9 2/3] usb: typec: tcpci: Add callback for evaluating
 contaminant presence

On 12/9/22 22:16, Badhri Jagan Sridharan wrote:
> This change adds callback to evaluate presence of contaminant in
> the TCPCI layer.
> 
> Signed-off-by: Badhri Jagan Sridharan <badhri@...gle.com>
> ---
> Changes since v7:
> * None. Skipped versions by mistake.
> Changes since v6:
> * Removed is_potential_contaminant callback
> Changes since v5:
> * None
> Changes since v4:
> * None
> Changes since v3:
> * None
> Changes since v2:
> * Added tcpci_is_potential_contaminant to offload
> * disconnect_while_debounce logic
> ---
>   drivers/usb/typec/tcpm/tcpci.c | 9 +++++++++
>   include/linux/usb/tcpci.h      | 7 +++++++
>   2 files changed, 16 insertions(+)
> 
> diff --git a/drivers/usb/typec/tcpm/tcpci.c b/drivers/usb/typec/tcpm/tcpci.c
> index fe781a38dc82..c8e78c13c9c4 100644
> --- a/drivers/usb/typec/tcpm/tcpci.c
> +++ b/drivers/usb/typec/tcpm/tcpci.c
> @@ -403,6 +403,14 @@ static void tcpci_frs_sourcing_vbus(struct tcpc_dev *dev)
>   		tcpci->data->frs_sourcing_vbus(tcpci, tcpci->data);
>   }
>   
> +static void tcpci_check_contaminant(struct tcpc_dev *dev)
> +{
> +	struct tcpci *tcpci = tcpc_to_tcpci(dev);
> +
> +	if (tcpci->data->check_contaminant)
> +		tcpci->data->check_contaminant(tcpci, tcpci->data);
> +}
> +

With this callback to tcpm in place, how does tcpm ever leave the
CHECK_CONTAMINANT state if the low level driver does not support
the callback ?

Thanks,
Guenter


>   static int tcpci_set_bist_data(struct tcpc_dev *tcpc, bool enable)
>   {
>   	struct tcpci *tcpci = tcpc_to_tcpci(tcpc);
> @@ -777,6 +785,7 @@ struct tcpci *tcpci_register_port(struct device *dev, struct tcpci_data *data)
>   	tcpci->tcpc.enable_frs = tcpci_enable_frs;
>   	tcpci->tcpc.frs_sourcing_vbus = tcpci_frs_sourcing_vbus;
>   	tcpci->tcpc.set_partner_usb_comm_capable = tcpci_set_partner_usb_comm_capable;
> +	tcpci->tcpc.check_contaminant = tcpci_check_contaminant;
>   
>   	if (tcpci->data->auto_discharge_disconnect) {
>   		tcpci->tcpc.enable_auto_vbus_discharge = tcpci_enable_auto_vbus_discharge;
> diff --git a/include/linux/usb/tcpci.h b/include/linux/usb/tcpci.h
> index 17657451c762..85e95a3251d3 100644
> --- a/include/linux/usb/tcpci.h
> +++ b/include/linux/usb/tcpci.h
> @@ -188,6 +188,12 @@ struct tcpci;
>    *		Optional; The USB Communications Capable bit indicates if port
>    *		partner is capable of communication over the USB data lines
>    *		(e.g. D+/- or SS Tx/Rx). Called to notify the status of the bit.
> + * @check_contaminant:
> + *		Optional; The callback is invoked when chiplevel drivers indicated
> + *		that the USB port needs to be checked for contaminant presence.
> + *		Chip level drivers are expected to check for contaminant and call
> + *		tcpm_clean_port when the port is clean to put the port back into
> + *		toggling state.
>    */
>   struct tcpci_data {
>   	struct regmap *regmap;
> @@ -204,6 +210,7 @@ struct tcpci_data {
>   	void (*frs_sourcing_vbus)(struct tcpci *tcpci, struct tcpci_data *data);
>   	void (*set_partner_usb_comm_capable)(struct tcpci *tcpci, struct tcpci_data *data,
>   					     bool capable);
> +	void (*check_contaminant)(struct tcpci *tcpci, struct tcpci_data *data);
>   };
>   
>   struct tcpci *tcpci_register_port(struct device *dev, struct tcpci_data *data);