usb: typec: maxim_contaminant: disable low power mode when reading comparator values

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: 02b332a ("usb: typec: maxim_contaminant: Implement check_contaminant callback")
Cc: stable <stable@kernel.org>
Signed-off-by: Amit Sunil Dhamne <amitsd@google.com>
Reviewed-by: Badhri Jagan Sridharan <badhri@google.com>
Rule: add
Link: https://lore.kernel.org/stable/20250814-fix-upstream-contaminant-v1-1-801ce8089031%40google.com
Link: https://lore.kernel.org/r/20250815-fix-upstream-contaminant-v2-1-6c8d6c3adafb@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: amitsd2

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);

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