usb: typec: tcpci: Prevent Sink disconnection before vPpsShutdown in SPR PPS

The Source can drop its output voltage to the minimum of the requested
PPS APDO voltage range when it is in Current Limit Mode. If this voltage
falls within the range of vPpsShutdown, the Source initiates a Hard
Reset and discharges Vbus. However, currently the Sink may disconnect
before the voltage reaches vPpsShutdown, leading to unexpected behavior.

Prevent premature disconnection by setting the Sink's disconnect
threshold to the minimum vPpsShutdown value. Additionally, consider the
voltage drop due to IR drop when calculating the appropriate threshold.
This ensures a robust and reliable interaction between the Source and
Sink during SPR PPS Current Limit Mode operation.

Fixes: 4288debeaa4e ("usb: typec: tcpci: Fix up sink disconnect thresholds for PD")
Cc: stable <stable@kernel.org>
Signed-off-by: Kyle Tso <kyletso@google.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: Badhri Jagan Sridharan <badhri@google.com>
Link: https://lore.kernel.org/r/20250114142435.2093857-1-kyletso@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/typec/tcpm/tcpci.c b/drivers/usb/typec/tcpm/tcpci.c
index 48762508cc8666fd9a6fd0ff00addac5f1d5d34f..19ab6647af706b0112440dcfebb47c996a31438c 100644 (file)
--- a/drivers/usb/typec/tcpm/tcpci.c
+++ b/drivers/usb/typec/tcpm/tcpci.c
@@ -27,6 +27,7 @@
 #define        VPPS_NEW_MIN_PERCENT                    95
 #define        VPPS_VALID_MIN_MV                       100
 #define        VSINKDISCONNECT_PD_MIN_PERCENT          90
+#define        VPPS_SHUTDOWN_MIN_PERCENT               85
 
 struct tcpci {
        struct device *dev;
@@ -366,7 +367,8 @@ static int tcpci_enable_auto_vbus_discharge(struct tcpc_dev *dev, bool enable)
 }
 
 static int tcpci_set_auto_vbus_discharge_threshold(struct tcpc_dev *dev, enum typec_pwr_opmode mode,
-                                                  bool pps_active, u32 requested_vbus_voltage_mv)
+                                                  bool pps_active, u32 requested_vbus_voltage_mv,
+                                                  u32 apdo_min_voltage_mv)
 {
        struct tcpci *tcpci = tcpc_to_tcpci(dev);
        unsigned int pwr_ctrl, threshold = 0;
@@ -388,9 +390,12 @@ static int tcpci_set_auto_vbus_discharge_threshold(struct tcpc_dev *dev, enum ty
                threshold = AUTO_DISCHARGE_DEFAULT_THRESHOLD_MV;
        } else if (mode == TYPEC_PWR_MODE_PD) {
                if (pps_active)
-                       threshold = ((VPPS_NEW_MIN_PERCENT * requested_vbus_voltage_mv / 100) -
-                                    VSINKPD_MIN_IR_DROP_MV - VPPS_VALID_MIN_MV) *
-                                    VSINKDISCONNECT_PD_MIN_PERCENT / 100;
+                       /*
+                        * To prevent disconnect when the source is in Current Limit Mode.
+                        * Set the threshold to the lowest possible voltage vPpsShutdown (min)
+                        */
+                       threshold = VPPS_SHUTDOWN_MIN_PERCENT * apdo_min_voltage_mv / 100 -
+                                   VSINKPD_MIN_IR_DROP_MV;
                else
                        threshold = ((VSRC_NEW_MIN_PERCENT * requested_vbus_voltage_mv / 100) -
                                     VSINKPD_MIN_IR_DROP_MV - VSRC_VALID_MIN_MV) *

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index ec14a4bc492f977b814d5ea085afbea2ffc59694..8f7c8ca2ba2acbd4336fd82e32fea1f7f49468aa 100644 (file)
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -2974,10 +2974,12 @@ static int tcpm_set_auto_vbus_discharge_threshold(struct tcpm_port *port,
                return 0;
 
        ret = port->tcpc->set_auto_vbus_discharge_threshold(port->tcpc, mode, pps_active,
-                                                           requested_vbus_voltage);
+                                                           requested_vbus_voltage,
+                                                           port->pps_data.min_volt);
        tcpm_log_force(port,
-                      "set_auto_vbus_discharge_threshold mode:%d pps_active:%c vbus:%u ret:%d",
-                      mode, pps_active ? 'y' : 'n', requested_vbus_voltage, ret);
+                      "set_auto_vbus_discharge_threshold mode:%d pps_active:%c vbus:%u pps_apdo_min_volt:%u ret:%d",
+                      mode, pps_active ? 'y' : 'n', requested_vbus_voltage,
+                      port->pps_data.min_volt, ret);
 
        return ret;
 }

diff --git a/include/linux/usb/tcpm.h b/include/linux/usb/tcpm.h
index 061da9546a813137645bfef5e6c024017d35a989..b22e659f81ba549d663175c7f55c3826251f6d14 100644 (file)
--- a/include/linux/usb/tcpm.h
+++ b/include/linux/usb/tcpm.h
@@ -163,7 +163,8 @@ struct tcpc_dev {
        void (*frs_sourcing_vbus)(struct tcpc_dev *dev);
        int (*enable_auto_vbus_discharge)(struct tcpc_dev *dev, bool enable);
        int (*set_auto_vbus_discharge_threshold)(struct tcpc_dev *dev, enum typec_pwr_opmode mode,
-                                                bool pps_active, u32 requested_vbus_voltage);
+                                                bool pps_active, u32 requested_vbus_voltage,
+                                                u32 pps_apdo_min_voltage);
        bool (*is_vbus_vsafe0v)(struct tcpc_dev *dev);
        void (*set_partner_usb_comm_capable)(struct tcpc_dev *dev, bool enable);
        void (*check_contaminant)(struct tcpc_dev *dev);