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

[ Upstream commit cabb6c5f4d9e7f49bdf8c0a13c74bd93ee35f45a ]

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 <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>
[ adapted macro names from CCLPMODESEL to CCLPMODESEL_MASK ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/typec/tcpm/maxim_contaminant.c b/drivers/usb/typec/tcpm/maxim_contaminant.c
index 279dfc84d1788919d05ff33a84bdc509fe1ce999..e37bf26cca805c8a60be3fe3edd7a7e3fe1a3c1e 100644 (file)
--- a/drivers/usb/typec/tcpm/maxim_contaminant.c
+++ b/drivers/usb/typec/tcpm/maxim_contaminant.c
@@ -5,6 +5,7 @@
  * USB-C module to reduce wakeups due to contaminants.
  */
 
+#include <linux/bitfield.h>
 #include <linux/device.h>
 #include <linux/irqreturn.h>
 #include <linux/module.h>
@@ -189,6 +190,11 @@ 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_MASK,
+                                FIELD_PREP(CCLPMODESEL_MASK,
+                                           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 2c1c4d161b0dcbcdaadb7616b59ef94e281b6ecf..861801cc456ff4fc7aac8d253f3b8c164fb1dc0c 100644 (file)
--- 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_MASK                        GENMASK(4, 3)
+#define LOW_POWER_MODE_DISABLE                  0
 #define ULTRA_LOW_POWER_MODE                    BIT(3)
 #define CCRPCTRL_MASK                           GENMASK(2, 0)
 #define UA_1_SRC                                1