linux-kernel - [PATCH v2] usb: typec: fusb302: Fix masking of comparator and bc

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Date:   Mon,  8 Nov 2021 11:28:32 +0100
From:   Ondrej Jirman <megous@...ous.com>
To:     Guenter Roeck <linux@...ck-us.net>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ondrej Jirman <megous@...ous.com>,
        Badhri Jagan Sridharan <badhri@...gle.com>,
        Hans de Goede <hdegoede@...hat.com>,
        linux-usb@...r.kernel.org (open list:USB TYPEC PORT CONTROLLER DRIVERS),
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v2] usb: typec: fusb302: Fix masking of comparator and bc_lvl interrupts

The code that enables either BC_LVL or COMP_CHNG interrupt in tcpm_set_cc
wrongly assumes that the interrupt is unmasked by writing 1 to the apropriate
bit in the mask register. In fact, interrupts are enabled when the mask
is 0, so the tcpm_set_cc enables interrupt for COMP_CHNG when it expects
BC_LVL interrupt to be enabled.

This causes inability of the driver to recognize cable unplug events
in host mode (unplug is recognized only via a COMP_CHNG interrupt).

In device mode this bug was masked by simultaneous triggering of the VBUS
change interrupt, because of loss of VBUS when the port peer is providing
power.

Fixes: 48242e30532b ("usb: typec: fusb302: Revert "Resolve fixed power role contract setup"")
Signed-off-by: Ondrej Jirman <megous@...ous.com>
Cc: Hans de Goede <hdegoede@...hat.com>
---
 drivers/usb/typec/tcpm/fusb302.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/typec/tcpm/fusb302.c b/drivers/usb/typec/tcpm/fusb302.c
index 7a2a17866a823..72f9001b07921 100644
--- a/drivers/usb/typec/tcpm/fusb302.c
+++ b/drivers/usb/typec/tcpm/fusb302.c
@@ -669,25 +669,27 @@ static int tcpm_set_cc(struct tcpc_dev *dev, enum typec_cc_status cc)
 		ret = fusb302_i2c_mask_write(chip, FUSB_REG_MASK,
 					     FUSB_REG_MASK_BC_LVL |
 					     FUSB_REG_MASK_COMP_CHNG,
-					     FUSB_REG_MASK_COMP_CHNG);
+					     FUSB_REG_MASK_BC_LVL);
 		if (ret < 0) {
 			fusb302_log(chip, "cannot set SRC interrupt, ret=%d",
 				    ret);
 			goto done;
 		}
 		chip->intr_comp_chng = true;
+		chip->intr_bc_lvl = false;
 		break;
 	case TYPEC_CC_RD:
 		ret = fusb302_i2c_mask_write(chip, FUSB_REG_MASK,
 					     FUSB_REG_MASK_BC_LVL |
 					     FUSB_REG_MASK_COMP_CHNG,
-					     FUSB_REG_MASK_BC_LVL);
+					     FUSB_REG_MASK_COMP_CHNG);
 		if (ret < 0) {
 			fusb302_log(chip, "cannot set SRC interrupt, ret=%d",
 				    ret);
 			goto done;
 		}
 		chip->intr_bc_lvl = true;
+		chip->intr_comp_chng = false;
 		break;
 	default:
 		break;
-- 
2.33.1