Commit cabb6c5f authored by Amit Sunil Dhamne's avatar Amit Sunil Dhamne Committed by Greg Kroah-Hartman
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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: 02b332a0 ("usb: typec: maxim_contaminant: Implement check_contaminant callback")
Cc: stable <stable@kernel.org>
Signed-off-by: default avatarAmit Sunil Dhamne <amitsd@google.com>
Reviewed-by: default avatarBadhri 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: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 45eae113

drivers/usb/typec/tcpm/maxim_contaminant.c

+5 −0
Original line number Diff line number Diff line
@@ -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

+1 −0
Original line number Diff line number Diff line
@@ -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