linux-kernel - [PATCH] usb: typec: ucsi: psy: Set current max to 100mA for BC 1.2 and Default

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250717200805.3710473-1-bleung@chromium.org>
Date: Thu, 17 Jul 2025 20:08:05 +0000
From: Benson Leung <bleung@...omium.org>
To: heikki.krogerus@...ux.intel.com,
	jthies@...gle.com,
	gregkh@...uxfoundation.org,
	hansg@...nel.org,
	sebastian.reichel@...labora.com,
	dmitry.baryshkov@....qualcomm.com,
	madhu.m@...el.com,
	linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: bleung@...gle.com,
	Benson Leung <bleung@...omium.org>
Subject: [PATCH] usb: typec: ucsi: psy: Set current max to 100mA for BC 1.2 and Default

ucsi_psy_get_current_max would return 0mA as the maximum current if
UCSI detected a BC or a Default USB Power sporce.

The comment in this function is true that we can't tell the difference
between DCP/CDP or SDP chargers, but we can guarantee that at least 1-unit
of USB 1.1/2.0 power is available, which is 100mA, which is a better
fallback value than 0, which causes some userspaces, including the ChromeOS
power manager, to regard this as a power source that is not providing
any power.

In reality, 100mA is guaranteed from all sources in these classes.

Signed-off-by: Benson Leung <bleung@...omium.org>
---
 drivers/usb/typec/ucsi/psy.c  | 2 +-
 drivers/usb/typec/ucsi/ucsi.h | 7 ++++---
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/typec/ucsi/psy.c b/drivers/usb/typec/ucsi/psy.c
index 62ac69730405..62a9d68bb66d 100644
--- a/drivers/usb/typec/ucsi/psy.c
+++ b/drivers/usb/typec/ucsi/psy.c
@@ -164,7 +164,7 @@ static int ucsi_psy_get_current_max(struct ucsi_connector *con,
 	case UCSI_CONSTAT_PWR_OPMODE_DEFAULT:
 	/* UCSI can't tell b/w DCP/CDP or USB2/3x1/3x2 SDP chargers */
 	default:
-		val->intval = 0;
+		val->intval = UCSI_TYPEC_DEFAULT_CURRENT * 1000;
 		break;
 	}
 	return 0;
diff --git a/drivers/usb/typec/ucsi/ucsi.h b/drivers/usb/typec/ucsi/ucsi.h
index b711e1ecc378..ebd7c27c2cc7 100644
--- a/drivers/usb/typec/ucsi/ucsi.h
+++ b/drivers/usb/typec/ucsi/ucsi.h
@@ -483,9 +483,10 @@ struct ucsi {
 #define UCSI_MAX_SVID		5
 #define UCSI_MAX_ALTMODES	(UCSI_MAX_SVID * 6)
 
-#define UCSI_TYPEC_VSAFE5V	5000
-#define UCSI_TYPEC_1_5_CURRENT	1500
-#define UCSI_TYPEC_3_0_CURRENT	3000
+#define UCSI_TYPEC_VSAFE5V		5000
+#define UCSI_TYPEC_DEFAULT_CURRENT	 100
+#define UCSI_TYPEC_1_5_CURRENT		1500
+#define UCSI_TYPEC_3_0_CURRENT		3000
 
 struct ucsi_connector {
 	int num;
-- 
2.50.0.727.gbf7dc18ff4-goog