On Thu, Feb 18, 2021 at 02:02:43AM -0800, Badhri Jagan Sridharan wrote:

When vbus auto discharge is enabled, TCPM can sometimes be faster than
the TCPC i.e. TCPM can go ahead and move the port to unattached state
(involves disabling vbus auto discharge) before TCPC could effectively
discharge vbus to VSAFE0V. This leaves vbus with residual charge and
increases the decay time which prevents tsafe0v from being met.
This change introduces a new state VBUS_DISCHARGE where the TCPM waits
for a maximum of tSafe0V(max) for vbus to discharge to VSAFE0V before
transitioning to unattached state and re-enable toggling. If vbus
discharges to vsafe0v sooner, then, transition to unattached state
happens right away.

Also, while in SNK_READY, when auto discharge is enabled, drive
disconnect based on vbus turning off instead of Rp disappearing on
CC pins. Rp disappearing on CC pins is almost instanteous compared
to vbus decay.

Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
---
 drivers/usb/typec/tcpm/tcpm.c | 60 +++++++++++++++++++++++++++++++----
 1 file changed, 53 insertions(+), 7 deletions(-)

As this seems to be a bugfix, what commit does it fix?  Should it go to
stable kernels?  If so, how far back?

And as this is the merge window, I can't do anything with this until
5.12-rc1 is out, so be prepared for the delay...

thanks,

greg k-h