On Fri, Aug 15, 2025 at 11:31:51AM -0700, Amit Sunil Dhamne via B4 Relay wrote:

From: Amit Sunil Dhamne amitsd@google.com

Low power mode is enabled when reading CC resistance as part of `max_contaminant_read_resistance_kohm()` and left in that state. However, it's supposed to work with 1uA current source. To read CC comparator values current source is changed to 80uA. This causes a storm of CC interrupts as it (falsely) detects a potential contaminant. To prevent this, disable low power mode current sourcing before reading comparator values.

Fixes: 02b332a06397 ("usb: typec: maxim_contaminant: Implement check_contaminant callback") Cc: stable@vger.kernel.org Signed-off-by: Amit Sunil Dhamne amitsd@google.com Reviewed-by: Badhri Jagan Sridharan badhri@google.com

Reviewed-by: Heikki Krogerus heikki.krogerus@linux.intel.com

---

drivers/usb/typec/tcpm/maxim_contaminant.c | 5 +++++ drivers/usb/typec/tcpm/tcpci_maxim.h | 1 + 2 files changed, 6 insertions(+)

diff --git a/drivers/usb/typec/tcpm/maxim_contaminant.c b/drivers/usb/typec/tcpm/maxim_contaminant.c index 0cdda06592fd3cc34e2179ccd49ef677f8ec9792..818cfe226ac7716de2fcbce205c67ea16acba592 100644 --- a/drivers/usb/typec/tcpm/maxim_contaminant.c +++ b/drivers/usb/typec/tcpm/maxim_contaminant.c @@ -188,6 +188,11 @@ static int max_contaminant_read_comparators(struct max_tcpci_chip *chip, u8 *ven if (ret < 0) return ret;

• /* Disable low power mode */
• ret = regmap_update_bits(regmap, TCPC_VENDOR_CC_CTRL2, CCLPMODESEL,

• 		 FIELD_PREP(CCLPMODESEL,
  

• 			    LOW_POWER_MODE_DISABLE));
  

• /* Sleep to allow comparators settle */ usleep_range(5000, 6000); ret = regmap_update_bits(regmap, TCPC_TCPC_CTRL, TCPC_TCPC_CTRL_ORIENTATION, PLUG_ORNT_CC1);

diff --git a/drivers/usb/typec/tcpm/tcpci_maxim.h b/drivers/usb/typec/tcpm/tcpci_maxim.h index 76270d5c283880dc49b13cabe7d682f2c2bf15fe..b33540a42a953dc6d8197790ee4af3b6f52791ce 100644 --- a/drivers/usb/typec/tcpm/tcpci_maxim.h +++ b/drivers/usb/typec/tcpm/tcpci_maxim.h @@ -21,6 +21,7 @@ #define CCOVPDIS BIT(6) #define SBURPCTRL BIT(5) #define CCLPMODESEL GENMASK(4, 3) +#define LOW_POWER_MODE_DISABLE 0 #define ULTRA_LOW_POWER_MODE 1 #define CCRPCTRL GENMASK(2, 0) #define UA_1_SRC 1

-- 2.51.0.rc1.167.g924127e9c0-goog

On Fri, Aug 15, 2025 at 11:31:52AM -0700, Amit Sunil Dhamne via B4 Relay wrote:

From: Amit Sunil Dhamne amitsd@google.com

Presently in `max_contaminant_is_contaminant()` if there's no contaminant detected previously, CC is open & stopped toggling and no contaminant is currently present, TCPC.RC would be programmed to do DRP toggling. However, it didn't actively look for a connection. This would lead to Type-C not detect *any* new connections. Hence, in the above situation, re-enable toggling & program TCPC to look for a new connection.

Also, return early if TCPC was looking for connection as this indicates TCPC has neither detected a potential connection nor a change in contaminant state.

In addition, once dry detection is complete (port is dry), restart toggling.

Fixes: 02b332a06397e ("usb: typec: maxim_contaminant: Implement check_contaminant callback") Cc: stable@vger.kernel.org Signed-off-by: Amit Sunil Dhamne amitsd@google.com Reviewed-by: Badhri Jagan Sridharan badhri@google.com

Reviewed-by: Heikki Krogerus heikki.krogerus@linux.intel.com

---

drivers/usb/typec/tcpm/maxim_contaminant.c | 53 ++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+)

diff --git a/drivers/usb/typec/tcpm/maxim_contaminant.c b/drivers/usb/typec/tcpm/maxim_contaminant.c index 818cfe226ac7716de2fcbce205c67ea16acba592..af8da6dc60ae0bc5900f6614514d51f41eded8ab 100644 --- a/drivers/usb/typec/tcpm/maxim_contaminant.c +++ b/drivers/usb/typec/tcpm/maxim_contaminant.c @@ -329,6 +329,39 @@ static int max_contaminant_enable_dry_detection(struct max_tcpci_chip *chip) return 0; } +static int max_contaminant_enable_toggling(struct max_tcpci_chip *chip) +{

• struct regmap *regmap = chip->data.regmap;
• int ret;
• /* Disable dry detection if enabled. */
• ret = regmap_update_bits(regmap, TCPC_VENDOR_CC_CTRL2, CCLPMODESEL,

• 		 FIELD_PREP(CCLPMODESEL,
  

• 			    LOW_POWER_MODE_DISABLE));
  

• if (ret)

• return ret;
  

• ret = regmap_update_bits(regmap, TCPC_VENDOR_CC_CTRL1, CCCONNDRY, 0);
• if (ret)

• return ret;
  

• ret = max_tcpci_write8(chip, TCPC_ROLE_CTRL, TCPC_ROLE_CTRL_DRP |

• 	       FIELD_PREP(TCPC_ROLE_CTRL_CC1,
  

• 			  TCPC_ROLE_CTRL_CC_RD) |
  

• 	       FIELD_PREP(TCPC_ROLE_CTRL_CC2,
  

• 			  TCPC_ROLE_CTRL_CC_RD));
  

• if (ret)

• return ret;
  

• ret = regmap_update_bits(regmap, TCPC_TCPC_CTRL,

• 		 TCPC_TCPC_CTRL_EN_LK4CONN_ALRT,
  

• 		 TCPC_TCPC_CTRL_EN_LK4CONN_ALRT);
  

• if (ret)

• return ret;
  

• return max_tcpci_write8(chip, TCPC_COMMAND, TCPC_CMD_LOOK4CONNECTION);

+}

bool max_contaminant_is_contaminant(struct max_tcpci_chip *chip, bool disconnect_while_debounce, bool *cc_handled) { @@ -345,6 +378,12 @@ bool max_contaminant_is_contaminant(struct max_tcpci_chip *chip, bool disconnect if (ret < 0) return false;

• if (cc_status & TCPC_CC_STATUS_TOGGLING) {

• if (chip->contaminant_state == DETECTED)
  

• 	return true;
  

• return false;
  

• }
• if (chip->contaminant_state == NOT_DETECTED || chip->contaminant_state == SINK) { if (!disconnect_while_debounce) msleep(100);

@@ -377,6 +416,12 @@ bool max_contaminant_is_contaminant(struct max_tcpci_chip *chip, bool disconnect max_contaminant_enable_dry_detection(chip); return true; }

• 	ret = max_contaminant_enable_toggling(chip);
  

• 	if (ret)
  

• 		dev_err(chip->dev,
  

• 			"Failed to enable toggling, ret=%d",
  

• 			ret);
  

  } } else if (chip->contaminant_state == DETECTED) { if (!(cc_status & TCPC_CC_STATUS_TOGGLING)) {

@@ -384,6 +429,14 @@ bool max_contaminant_is_contaminant(struct max_tcpci_chip *chip, bool disconnect if (chip->contaminant_state == DETECTED) { max_contaminant_enable_dry_detection(chip); return true;

• 	} else {
  

• 		ret = max_contaminant_enable_toggling(chip);
  

• 		if (ret) {
  

• 			dev_err(chip->dev,
  

• 				"Failed to enable toggling, ret=%d",
  

• 				ret);
  

• 			return true;
  

• 		}
  }
  

  } }

-- 2.51.0.rc1.167.g924127e9c0-goog