linux-kernel - [RESEND v2] usb:typec:tcpm:support double Rp to Vbus cable as sink

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Message-Id: <20230920063030.66312-1-michael@allwinnertech.com>
Date:   Wed, 20 Sep 2023 14:30:30 +0800
From:   Michael Wu <michael@...winnertech.com>
To:     linux@...ck-us.net, heikki.krogerus@...ux.intel.com,
        gregkh@...uxfoundation.org
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [RESEND v2] usb:typec:tcpm:support double Rp to Vbus cable as sink

The USB Type-C Cable and Connector Specification defines the wire
connections for the USB Type-C to USB 2.0 Standard-A cable assembly
(Release 2.2, Chapter 3.5.2).
The Notes says that Pin A5 (CC) of the USB Type-C plug shall be connected
to Vbus through a resister Rp.
However, there is a large amount of such double Rp connected to Vbus
non-standard cables which produced by UGREEN circulating on the market, and
it can affects the normal operations of the state machine easily,
especially to CC1 and CC2 be pulled up at the same time.
In fact, we can regard those cables as sink to avoid abnormal state.

Message as follow:
[   58.900212] VBUS on
[   59.265433] CC1: 0 -> 3, CC2: 0 -> 3 [state TOGGLING, polarity 0, connected]
[   62.623308] CC1: 3 -> 0, CC2: 3 -> 0 [state TOGGLING, polarity 0, disconnected]
[   62.625006] VBUS off
[   62.625012] VBUS VSAFE0V

Signed-off-by: Michael Wu <michael@...winnertech.com>
---
v1 -> v2: Simplify expression and add a comment to the code.

 drivers/usb/typec/tcpm/tcpm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Signed-off-by: Michael Wu <michael@...winnertech.com>
---
 drivers/usb/typec/tcpm/tcpm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index d962f67c95ae6..6e843c511b856 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -517,9 +517,9 @@ static const char * const pd_rev[] = {
 	((cc) == TYPEC_CC_RP_DEF || (cc) == TYPEC_CC_RP_1_5 || \
 	 (cc) == TYPEC_CC_RP_3_0)
 
+/* As long as cc is pulled up, we can consider it as sink. */
 #define tcpm_port_is_sink(port) \
-	((tcpm_cc_is_sink((port)->cc1) && !tcpm_cc_is_sink((port)->cc2)) || \
-	 (tcpm_cc_is_sink((port)->cc2) && !tcpm_cc_is_sink((port)->cc1)))
+	(tcpm_cc_is_sink((port)->cc1) || tcpm_cc_is_sink((port)->cc2))
 
 #define tcpm_cc_is_source(cc) ((cc) == TYPEC_CC_RD)
 #define tcpm_cc_is_audio(cc) ((cc) == TYPEC_CC_RA)
-- 
2.29.0