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