Re: [PATCH] platform/chrome: cros_ec_typec: deferred probe when typec count mismatch

From: Ruihai Zhou
Date: Tue Dec 20 2022 - 21:58:45 EST


> I think that is problematic. It might as well be that nports >
> EC_USB_PD_MAX_PORTS.
Yes, you're right. so we should consider it's a invalid argument and return -EINVAL
if nports > EC_USB_PD_MAX_PORTS. right?
> Is this really seen in the field ? The EC should never report a wrong
> (random) number of ports. If it is not ready, there should be _some_
> indication that it isn't ready. Does it really report a more or less
> random number in this case ?
Yes, I saw this on corsola boards. The EC report a wrong(not random) number.
because corsola emulates HDMI MUX over the current type-c mux stack. The ec has to
fake a type-c port to pass the MUX info. But the task are not initiated on starting up,
and increase the type-c port counts after the tasks finished. In this case, I saw
the typec->num_ports = 1, but the nports = 2, which will be probe failed and block
the HDMI MUX function.
I will send v2 patch, if nports > EC_USB_PD_MAX_PORTS, then return -EINVAL,
but if nports > typec->num_ports, we consider wait a second to ec task increase the
type-c port counts if there're HDMI DB attach, then return -EPROBE_DEFER.