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Message-ID: <f05e66b9-1357-4d0d-7b9b-63ccf976a27c@roeck-us.net>
Date: Fri, 9 Dec 2022 05:44:05 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Badhri Jagan Sridharan <badhri@...gle.com>
Cc: Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
Kyle Tso <kyletso@...gle.com>
Subject: Re: [PATCH v6 1/3] usb: typec: tcpm: Add callbacks to mitigate
wakeups due to contaminant
On 12/8/22 18:39, Badhri Jagan Sridharan wrote:
> On Thu, Dec 8, 2022 at 3:56 PM Guenter Roeck <linux@...ck-us.net> wrote:
>>
>> On 12/8/22 07:04, Badhri Jagan Sridharan wrote:
>>> On some of the TCPC implementations, when the Type-C port is exposed
>>> to contaminants, such as water, TCPC stops toggling while reporting OPEN
>>> either by the time TCPM reads CC pin status or during CC debounce
>>> window. This causes TCPM to be stuck in TOGGLING state. If TCPM is made
>>> to restart toggling, the behavior recurs causing redundant CPU wakeups
>>> till the USB-C port is free of contaminant.
>>>
>>> [206199.287817] CC1: 0 -> 0, CC2: 0 -> 0 [state TOGGLING, polarity 0, disconnected]
>>> [206199.640337] CC1: 0 -> 0, CC2: 0 -> 0 [state TOGGLING, polarity 0, disconnected]
>>> [206199.985789] CC1: 0 -> 0, CC2: 0 -> 0 [state TOGGLING, polarity 0, disconnected]
>>> ...
>>>
>>> TCPM invokes is_potential_contaminant callback to allow low level chip
>>> drivers to monitor TCPM state machine transitions and notify TCPM when
>>> the Type-C port needs to be checked for potential contaminant presence.
>>> TCPCs which do have the needed hardware can implement the check_contaminant
>>> callback which is invoked by TCPM to evaluate for presence of contaminant.
>>> Lower level TCPC driver can restart toggling through TCPM_PORT_CLEAN event
>>> when the driver detects that USB-C port is free of contaminant.
>>>
>>> Signed-off-by: Badhri Jagan Sridharan <badhri@...gle.com>
>>> ---
>>> Changes since v5:
>>> * Updated commit message. Removed change id.
>>> Changes since v4:
>>> * None
>>> Changes since v3:
>>> * None
>>> Changes since V2:
>>> * Offloaded tcpm from maintaining disconnect_while_debouncing logic
>>> * to lower level maxim tcpc driver based on feedback.
>>> ---
>>> drivers/usb/typec/tcpm/tcpm.c | 162 +++++++++-------------------------
>>> include/linux/usb/tcpm.h | 133 ++++++++++++++++++++++++++++
>>> 2 files changed, 177 insertions(+), 118 deletions(-)
>>>
>>> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
>>> index 904c7b4ce2f0..a138cea49612 100644
>>> --- a/drivers/usb/typec/tcpm/tcpm.c
>>> +++ b/drivers/usb/typec/tcpm/tcpm.c
>>> @@ -33,119 +33,6 @@
>>>
>>> #include <uapi/linux/sched/types.h>
>>>
>>> -#define FOREACH_STATE(S) \
>>> - S(INVALID_STATE), \
>>> - S(TOGGLING), \
>>> - S(SRC_UNATTACHED), \
>>> - S(SRC_ATTACH_WAIT), \
>>> - S(SRC_ATTACHED), \
>>> - S(SRC_STARTUP), \
>>> - S(SRC_SEND_CAPABILITIES), \
>>> - S(SRC_SEND_CAPABILITIES_TIMEOUT), \
>>> - S(SRC_NEGOTIATE_CAPABILITIES), \
>>> - S(SRC_TRANSITION_SUPPLY), \
>>> - S(SRC_READY), \
>>> - S(SRC_WAIT_NEW_CAPABILITIES), \
>>> - \
>>> - S(SNK_UNATTACHED), \
>>> - S(SNK_ATTACH_WAIT), \
>>> - S(SNK_DEBOUNCED), \
>>> - S(SNK_ATTACHED), \
>>> - S(SNK_STARTUP), \
>>> - S(SNK_DISCOVERY), \
>>> - S(SNK_DISCOVERY_DEBOUNCE), \
>>> - S(SNK_DISCOVERY_DEBOUNCE_DONE), \
>>> - S(SNK_WAIT_CAPABILITIES), \
>>> - S(SNK_NEGOTIATE_CAPABILITIES), \
>>> - S(SNK_NEGOTIATE_PPS_CAPABILITIES), \
>>> - S(SNK_TRANSITION_SINK), \
>>> - S(SNK_TRANSITION_SINK_VBUS), \
>>> - S(SNK_READY), \
>>> - \
>>> - S(ACC_UNATTACHED), \
>>> - S(DEBUG_ACC_ATTACHED), \
>>> - S(AUDIO_ACC_ATTACHED), \
>>> - S(AUDIO_ACC_DEBOUNCE), \
>>> - \
>>> - S(HARD_RESET_SEND), \
>>> - S(HARD_RESET_START), \
>>> - S(SRC_HARD_RESET_VBUS_OFF), \
>>> - S(SRC_HARD_RESET_VBUS_ON), \
>>> - S(SNK_HARD_RESET_SINK_OFF), \
>>> - S(SNK_HARD_RESET_WAIT_VBUS), \
>>> - S(SNK_HARD_RESET_SINK_ON), \
>>> - \
>>> - S(SOFT_RESET), \
>>> - S(SRC_SOFT_RESET_WAIT_SNK_TX), \
>>> - S(SNK_SOFT_RESET), \
>>> - S(SOFT_RESET_SEND), \
>>> - \
>>> - S(DR_SWAP_ACCEPT), \
>>> - S(DR_SWAP_SEND), \
>>> - S(DR_SWAP_SEND_TIMEOUT), \
>>> - S(DR_SWAP_CANCEL), \
>>> - S(DR_SWAP_CHANGE_DR), \
>>> - \
>>> - S(PR_SWAP_ACCEPT), \
>>> - S(PR_SWAP_SEND), \
>>> - S(PR_SWAP_SEND_TIMEOUT), \
>>> - S(PR_SWAP_CANCEL), \
>>> - S(PR_SWAP_START), \
>>> - S(PR_SWAP_SRC_SNK_TRANSITION_OFF), \
>>> - S(PR_SWAP_SRC_SNK_SOURCE_OFF), \
>>> - S(PR_SWAP_SRC_SNK_SOURCE_OFF_CC_DEBOUNCED), \
>>> - S(PR_SWAP_SRC_SNK_SINK_ON), \
>>> - S(PR_SWAP_SNK_SRC_SINK_OFF), \
>>> - S(PR_SWAP_SNK_SRC_SOURCE_ON), \
>>> - S(PR_SWAP_SNK_SRC_SOURCE_ON_VBUS_RAMPED_UP), \
>>> - \
>>> - S(VCONN_SWAP_ACCEPT), \
>>> - S(VCONN_SWAP_SEND), \
>>> - S(VCONN_SWAP_SEND_TIMEOUT), \
>>> - S(VCONN_SWAP_CANCEL), \
>>> - S(VCONN_SWAP_START), \
>>> - S(VCONN_SWAP_WAIT_FOR_VCONN), \
>>> - S(VCONN_SWAP_TURN_ON_VCONN), \
>>> - S(VCONN_SWAP_TURN_OFF_VCONN), \
>>> - \
>>> - S(FR_SWAP_SEND), \
>>> - S(FR_SWAP_SEND_TIMEOUT), \
>>> - S(FR_SWAP_SNK_SRC_TRANSITION_TO_OFF), \
>>> - S(FR_SWAP_SNK_SRC_NEW_SINK_READY), \
>>> - S(FR_SWAP_SNK_SRC_SOURCE_VBUS_APPLIED), \
>>> - S(FR_SWAP_CANCEL), \
>>> - \
>>> - S(SNK_TRY), \
>>> - S(SNK_TRY_WAIT), \
>>> - S(SNK_TRY_WAIT_DEBOUNCE), \
>>> - S(SNK_TRY_WAIT_DEBOUNCE_CHECK_VBUS), \
>>> - S(SRC_TRYWAIT), \
>>> - S(SRC_TRYWAIT_DEBOUNCE), \
>>> - S(SRC_TRYWAIT_UNATTACHED), \
>>> - \
>>> - S(SRC_TRY), \
>>> - S(SRC_TRY_WAIT), \
>>> - S(SRC_TRY_DEBOUNCE), \
>>> - S(SNK_TRYWAIT), \
>>> - S(SNK_TRYWAIT_DEBOUNCE), \
>>> - S(SNK_TRYWAIT_VBUS), \
>>> - S(BIST_RX), \
>>> - \
>>> - S(GET_STATUS_SEND), \
>>> - S(GET_STATUS_SEND_TIMEOUT), \
>>> - S(GET_PPS_STATUS_SEND), \
>>> - S(GET_PPS_STATUS_SEND_TIMEOUT), \
>>> - \
>>> - S(GET_SINK_CAP), \
>>> - S(GET_SINK_CAP_TIMEOUT), \
>>> - \
>>> - S(ERROR_RECOVERY), \
>>> - S(PORT_RESET), \
>>> - S(PORT_RESET_WAIT_OFF), \
>>> - \
>>> - S(AMS_START), \
>>> - S(CHUNK_NOT_SUPP)
>>> -
>>> #define FOREACH_AMS(S) \
>>> S(NONE_AMS), \
>>> S(POWER_NEGOTIATION), \
>>> @@ -182,13 +69,8 @@
>>> S(COUNTRY_INFO), \
>>> S(COUNTRY_CODES)
>>>
>>> -#define GENERATE_ENUM(e) e
>>> #define GENERATE_STRING(s) #s
>>>
>>> -enum tcpm_state {
>>> - FOREACH_STATE(GENERATE_ENUM)
>>> -};
>>> -
>>> static const char * const tcpm_states[] = {
>>> FOREACH_STATE(GENERATE_STRING)
>>> };
>>> @@ -249,6 +131,7 @@ enum frs_typec_current {
>>> #define TCPM_RESET_EVENT BIT(2)
>>> #define TCPM_FRS_EVENT BIT(3)
>>> #define TCPM_SOURCING_VBUS BIT(4)
>>> +#define TCPM_PORT_CLEAN BIT(5)
>>>
>>> #define LOG_BUFFER_ENTRIES 1024
>>> #define LOG_BUFFER_ENTRY_SIZE 128
>>> @@ -483,6 +366,14 @@ struct tcpm_port {
>>> * SNK_READY for non-pd link.
>>> */
>>> bool slow_charger_loop;
>>> +
>>> + /*
>>> + * When true indicates that the lower level drivers indicate potential presence
>>> + * of contaminant in the connector pins based on the tcpm state machine
>>> + * transitions.
>>> + */
>>> + bool potential_contaminant;
>>> +
>>> #ifdef CONFIG_DEBUG_FS
>>> struct dentry *dentry;
>>> struct mutex logbuffer_lock; /* log buffer access lock */
>>> @@ -3904,15 +3795,26 @@ static void run_state_machine(struct tcpm_port *port)
>>> unsigned int msecs;
>>> enum tcpm_state upcoming_state;
>>>
>>> + if (port->tcpc->is_potential_contaminant)
>>> + port->potential_contaminant =
>>> + port->tcpc->is_potential_contaminant(port->tcpc, port->state);
>>> +
>>> port->enter_state = port->state;
>>> switch (port->state) {
>>> case TOGGLING:
>>> break;
>>> + case CHECK_CONTAMINANT:
>>> + port->tcpc->check_contaminant(port->tcpc);
>>> + break;
>>> /* SRC states */
>>> case SRC_UNATTACHED:
>>> if (!port->non_pd_role_swap)
>>> tcpm_swap_complete(port, -ENOTCONN);
>>> tcpm_src_detach(port);
>>> + if (port->potential_contaminant && port->tcpc->check_contaminant) {
>>> + tcpm_set_state(port, CHECK_CONTAMINANT, 0);
>>> + break;
>>> + }
>>> if (tcpm_start_toggling(port, tcpm_rp_cc(port))) {
>>> tcpm_set_state(port, TOGGLING, 0);
>>> break;
>>> @@ -4150,6 +4052,10 @@ static void run_state_machine(struct tcpm_port *port)
>>> tcpm_swap_complete(port, -ENOTCONN);
>>> tcpm_pps_complete(port, -ENOTCONN);
>>> tcpm_snk_detach(port);
>>> + if (port->potential_contaminant && port->tcpc->check_contaminant) {
>>> + tcpm_set_state(port, CHECK_CONTAMINANT, 0);
>>> + break;
>>> + }
>>> if (tcpm_start_toggling(port, TYPEC_CC_RD)) {
>>> tcpm_set_state(port, TOGGLING, 0);
>>> break;
>>> @@ -4926,6 +4832,9 @@ static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1,
>>> else if (tcpm_port_is_sink(port))
>>> tcpm_set_state(port, SNK_ATTACH_WAIT, 0);
>>> break;
>>> + case CHECK_CONTAMINANT:
>>> + /* Wait for Toggling to be resumed */
>>> + break;
>>> case SRC_UNATTACHED:
>>> case ACC_UNATTACHED:
>>> if (tcpm_port_is_debug(port) || tcpm_port_is_audio(port) ||
>>> @@ -5425,6 +5334,10 @@ static void tcpm_pd_event_handler(struct kthread_work *work)
>>> port->vbus_source = true;
>>> _tcpm_pd_vbus_on(port);
>>> }
>>> + if (events & TCPM_PORT_CLEAN) {
>>> + tcpm_log(port, "port clean");
>>> + tcpm_set_state(port, TOGGLING, 0);
>>> + }
>>
>> That sets the state to TOGGLING unconditionally, even if it not currently
>> CHECK_CONTAMINANT. Is that a potential problem ?
>
> Good catch ! Would make sense to check whether tcpm is in
> CHECK_CONTAMINANT state before setting the TOGGLING state.
>>
>>>
>>> spin_lock(&port->pd_event_lock);
>>> }
>>> @@ -5477,6 +5390,19 @@ void tcpm_sourcing_vbus(struct tcpm_port *port)
>>> }
>>> EXPORT_SYMBOL_GPL(tcpm_sourcing_vbus);
>>>
>>> +/*
>>> + * Low level tcpc drivers invoke this once the port is deemed clean to return
>>> + * the port to TOGGLING state.
>>> + */
>>> +void tcpm_port_clean(struct tcpm_port *port)
>>> +{
>>> + spin_lock(&port->pd_event_lock);
>>> + port->pd_events |= TCPM_PORT_CLEAN;
>>> + spin_unlock(&port->pd_event_lock);
>>> + kthread_queue_work(port->wq, &port->event_work);
>>> +}
>>> +EXPORT_SYMBOL_GPL(tcpm_port_clean);
>>> +
>>> static void tcpm_enable_frs_work(struct kthread_work *work)
>>> {
>>> struct tcpm_port *port = container_of(work, struct tcpm_port, enable_frs);
>>> diff --git a/include/linux/usb/tcpm.h b/include/linux/usb/tcpm.h
>>> index bffc8d3e14ad..9cf16372a6e4 100644
>>> --- a/include/linux/usb/tcpm.h
>>> +++ b/include/linux/usb/tcpm.h
>>> @@ -10,6 +10,126 @@
>>> #include <linux/usb/typec.h>
>>> #include "pd.h"
>>>
>>> +#define FOREACH_STATE(S) \
>>> + S(INVALID_STATE), \
>>> + S(TOGGLING), \
>>> + S(CHECK_CONTAMINANT), \
>>> + S(SRC_UNATTACHED), \
>>> + S(SRC_ATTACH_WAIT), \
>>> + S(SRC_ATTACHED), \
>>> + S(SRC_STARTUP), \
>>> + S(SRC_SEND_CAPABILITIES), \
>>> + S(SRC_SEND_CAPABILITIES_TIMEOUT), \
>>> + S(SRC_NEGOTIATE_CAPABILITIES), \
>>> + S(SRC_TRANSITION_SUPPLY), \
>>> + S(SRC_READY), \
>>> + S(SRC_WAIT_NEW_CAPABILITIES), \
>>> + \
>>> + S(SNK_UNATTACHED), \
>>> + S(SNK_ATTACH_WAIT), \
>>> + S(SNK_DEBOUNCED), \
>>> + S(SNK_ATTACHED), \
>>> + S(SNK_STARTUP), \
>>> + S(SNK_DISCOVERY), \
>>> + S(SNK_DISCOVERY_DEBOUNCE), \
>>> + S(SNK_DISCOVERY_DEBOUNCE_DONE), \
>>> + S(SNK_WAIT_CAPABILITIES), \
>>> + S(SNK_NEGOTIATE_CAPABILITIES), \
>>> + S(SNK_NEGOTIATE_PPS_CAPABILITIES), \
>>> + S(SNK_TRANSITION_SINK), \
>>> + S(SNK_TRANSITION_SINK_VBUS), \
>>> + S(SNK_READY), \
>>> + \
>>> + S(ACC_UNATTACHED), \
>>> + S(DEBUG_ACC_ATTACHED), \
>>> + S(AUDIO_ACC_ATTACHED), \
>>> + S(AUDIO_ACC_DEBOUNCE), \
>>> + \
>>> + S(HARD_RESET_SEND), \
>>> + S(HARD_RESET_START), \
>>> + S(SRC_HARD_RESET_VBUS_OFF), \
>>> + S(SRC_HARD_RESET_VBUS_ON), \
>>> + S(SNK_HARD_RESET_SINK_OFF), \
>>> + S(SNK_HARD_RESET_WAIT_VBUS), \
>>> + S(SNK_HARD_RESET_SINK_ON), \
>>> + \
>>> + S(SOFT_RESET), \
>>> + S(SRC_SOFT_RESET_WAIT_SNK_TX), \
>>> + S(SNK_SOFT_RESET), \
>>> + S(SOFT_RESET_SEND), \
>>> + \
>>> + S(DR_SWAP_ACCEPT), \
>>> + S(DR_SWAP_SEND), \
>>> + S(DR_SWAP_SEND_TIMEOUT), \
>>> + S(DR_SWAP_CANCEL), \
>>> + S(DR_SWAP_CHANGE_DR), \
>>> + \
>>> + S(PR_SWAP_ACCEPT), \
>>> + S(PR_SWAP_SEND), \
>>> + S(PR_SWAP_SEND_TIMEOUT), \
>>> + S(PR_SWAP_CANCEL), \
>>> + S(PR_SWAP_START), \
>>> + S(PR_SWAP_SRC_SNK_TRANSITION_OFF), \
>>> + S(PR_SWAP_SRC_SNK_SOURCE_OFF), \
>>> + S(PR_SWAP_SRC_SNK_SOURCE_OFF_CC_DEBOUNCED), \
>>> + S(PR_SWAP_SRC_SNK_SINK_ON), \
>>> + S(PR_SWAP_SNK_SRC_SINK_OFF), \
>>> + S(PR_SWAP_SNK_SRC_SOURCE_ON), \
>>> + S(PR_SWAP_SNK_SRC_SOURCE_ON_VBUS_RAMPED_UP), \
>>> + \
>>> + S(VCONN_SWAP_ACCEPT), \
>>> + S(VCONN_SWAP_SEND), \
>>> + S(VCONN_SWAP_SEND_TIMEOUT), \
>>> + S(VCONN_SWAP_CANCEL), \
>>> + S(VCONN_SWAP_START), \
>>> + S(VCONN_SWAP_WAIT_FOR_VCONN), \
>>> + S(VCONN_SWAP_TURN_ON_VCONN), \
>>> + S(VCONN_SWAP_TURN_OFF_VCONN), \
>>> + \
>>> + S(FR_SWAP_SEND), \
>>> + S(FR_SWAP_SEND_TIMEOUT), \
>>> + S(FR_SWAP_SNK_SRC_TRANSITION_TO_OFF), \
>>> + S(FR_SWAP_SNK_SRC_NEW_SINK_READY), \
>>> + S(FR_SWAP_SNK_SRC_SOURCE_VBUS_APPLIED), \
>>> + S(FR_SWAP_CANCEL), \
>>> + \
>>> + S(SNK_TRY), \
>>> + S(SNK_TRY_WAIT), \
>>> + S(SNK_TRY_WAIT_DEBOUNCE), \
>>> + S(SNK_TRY_WAIT_DEBOUNCE_CHECK_VBUS), \
>>> + S(SRC_TRYWAIT), \
>>> + S(SRC_TRYWAIT_DEBOUNCE), \
>>> + S(SRC_TRYWAIT_UNATTACHED), \
>>> + \
>>> + S(SRC_TRY), \
>>> + S(SRC_TRY_WAIT), \
>>> + S(SRC_TRY_DEBOUNCE), \
>>> + S(SNK_TRYWAIT), \
>>> + S(SNK_TRYWAIT_DEBOUNCE), \
>>> + S(SNK_TRYWAIT_VBUS), \
>>> + S(BIST_RX), \
>>> + \
>>> + S(GET_STATUS_SEND), \
>>> + S(GET_STATUS_SEND_TIMEOUT), \
>>> + S(GET_PPS_STATUS_SEND), \
>>> + S(GET_PPS_STATUS_SEND_TIMEOUT), \
>>> + \
>>> + S(GET_SINK_CAP), \
>>> + S(GET_SINK_CAP_TIMEOUT), \
>>> + \
>>> + S(ERROR_RECOVERY), \
>>> + S(PORT_RESET), \
>>> + S(PORT_RESET_WAIT_OFF), \
>>> + \
>>> + S(AMS_START), \
>>> + S(CHUNK_NOT_SUPP)
>>> +
>>> +#define GENERATE_ENUM(e) e
>>> +
>>> +enum tcpm_state {
>>> + FOREACH_STATE(GENERATE_ENUM)
>>> +};
>>> +
>>
>> Sorry for not bringing it up earlier; I have been struggling with it all along,
>> and I could not decide if I should bring it up or not.
>>
>> I really don't feel comfortable with exporting states outside tcpm.
>> Is this really necessary ? The only use seems to be
>>
>> + if ((tcpm_prev_state == SRC_ATTACH_WAIT && current_state == SRC_UNATTACHED) ||
>> + (tcpm_prev_state == SNK_ATTACH_WAIT && current_state == SNK_UNATTACHED))
>>
>> Plus, of course, the CHECK_CONTAMINANT state.
>>
>> Is there reason to believe that the relevant state transitions would be different
>> for other chips ? If not, would it possibly make sense to move this check
>> into the state machine ?
>
> In my understanding, this is definitely one of the transitions that I
> think will happen when the port has contaminant. It's quite possible
> that there are transitions that I am not aware of yet.
> I am OK moving it back to the tcpm state machine, however, then tcpm
> would have to keep track of the tcpm state machine transitions and
> that would look like V2 version of the patch
> (https://lore.kernel.org/lkml/20220831001555.285081-1-badhri@google.com/)
> where disconnect_while_debouncing is used to track this. Would that be
> OK ?
>
Kind of, except that I think it was way too invasive. The current code checks for
contaminant once when entering the state machine. If you pull that code into the
state machine, I don't see why it would have to be more than a single call.
One possibility might be to move the call into tcpm_set_state() to catch all
state transitions, or to use the existing enter_state variable for that
purpose.
>>
>>> enum typec_cc_status {
>>> TYPEC_CC_OPEN,
>>> TYPEC_CC_RA,
>>> @@ -114,6 +234,16 @@ enum tcpm_transmit_type {
>>> * 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.
>>> + * @is_potential_contaminant:
>>> + * Optional; TCPM invokes the callback for every TCPM state machine
>>> + * transition. Chiplevel drivers can monitor the state machine
>>> + * transitions to flag for potential contaminant presence.
>>
>> I kind of dislike the repeated checks for those callbacks in the state machine.
>> Does it make any sense to have one of those callbacks but not the other ?
>>
>> Because if not it might make sense to check in the registration function
>> if either both are NULL or both are set, and then drop most of the checks
>> in the state machine handler.
>
> I can definitely check for the registration of the callbacks but cant
> drop one of them unless we are OK to make tcpm transitions and invoke
> the check_contaminant callback directly.
>
I didn't necessarily mean to drop one of the callbacks (unless one of them is
pulled into the tcpm driver). I envisioned a check such as
if ((!tcpc->check_contaminant && tcpc->is_potential_contaminant) ||
((tcpc->check_contaminant && !tcpc->is_potential_contaminant))
return ERR_PTR(-EINVAL);
in tcpm_register_port().
With that, it would no longer be necessary to keep checking for
port->tcpc->check_contaminant later on because potential_contaminant would only
ever be true if the check_contaminant callback exists.
Another note: We currently don't log in SRC_UNATTACHED, SNK_UNATTACHED,
and TOGGLING states. Would it make sense to add CHECK_CONTAMINANT to
the checks in tcpm_log() ?
Thanks,
Guenter
> Thanks,
> Badhri
>
>
>>
>> Thanks,
>> Guenter
>>
>>> */
>>> struct tcpc_dev {
>>> struct fwnode_handle *fwnode;
>>> @@ -148,6 +278,8 @@ struct tcpc_dev {
>>> bool pps_active, u32 requested_vbus_voltage);
>>> bool (*is_vbus_vsafe0v)(struct tcpc_dev *dev);
>>> void (*set_partner_usb_comm_capable)(struct tcpc_dev *dev, bool enable);
>>> + void (*check_contaminant)(struct tcpc_dev *dev);
>>> + bool (*is_potential_contaminant)(struct tcpc_dev *dev, enum tcpm_state current_state);
>>> };
>>>
>>> struct tcpm_port;
>>> @@ -165,5 +297,6 @@ void tcpm_pd_transmit_complete(struct tcpm_port *port,
>>> enum tcpm_transmit_status status);
>>> void tcpm_pd_hard_reset(struct tcpm_port *port);
>>> void tcpm_tcpc_reset(struct tcpm_port *port);
>>> +void tcpm_port_clean(struct tcpm_port *port);
>>>
>>> #endif /* __LINUX_USB_TCPM_H */
>>>
>>> base-commit: 1524ceb14dd5ebd6f724d993c5ec1a9a8d445d8e
>>
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