On 9/18/23 03:31, Heikki Krogerus wrote:
On Thu, Sep 14, 2023 at 08:31:54AM +0800, Michael Wu wrote:
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@xxxxxxxxxxxxxxxxx>
---
drivers/usb/typec/tcpm/tcpm.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index d962f67c95ae6..beb7143128667 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -519,7 +519,8 @@ static const char * const pd_rev[] = {
#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)->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)
This look OK to me, but I would still like to wait for comments from
Guenter - just in case.
Look at the conditions. Reordered, we end up with
(tcpm_cc_is_sink((port)->cc1) && !tcpm_cc_is_sink((port)->cc2)) ||
(tcpm_cc_is_sink((port)->cc1) && tcpm_cc_is_sink((port)->cc2))
which simplifies to
tcpm_cc_is_sink((port)->cc1)
making the complete expression
tcpm_cc_is_sink((port)->cc1) ||
(tcpm_cc_is_sink((port)->cc2) && !tcpm_cc_is_sink((port)->cc1))
which simplifies further to
tcpm_cc_is_sink((port)->cc1) || tcpm_cc_is_sink((port)->cc2)
The simplified expression doesn't conflict with other detections, so I am
ok with it. It might be worthwhile adding a comment to the code, though,
explaining the reason.
Guenter
thanks,
