On Mon, Nov 15, 2021 at 09:11:42AM +0200, Heikki Krogerus wrote:
> On Mon, Nov 08, 2021 at 11:28:32AM +0100, Ondrej Jirman wrote:
> > The code that enables either BC_LVL or COMP_CHNG interrupt in tcpm_set_cc
> > wrongly assumes that the interrupt is unmasked by writing 1 to the apropriate
> > bit in the mask register. In fact, interrupts are enabled when the mask
> > is 0, so the tcpm_set_cc enables interrupt for COMP_CHNG when it expects
> > BC_LVL interrupt to be enabled.
> >
> > This causes inability of the driver to recognize cable unplug events
> > in host mode (unplug is recognized only via a COMP_CHNG interrupt).
> >
> > In device mode this bug was masked by simultaneous triggering of the VBUS
> > change interrupt, because of loss of VBUS when the port peer is providing
> > power.
> >
> > Fixes: 48242e30532b ("usb: typec: fusb302: Revert "Resolve fixed power role contract setup"")
> > Signed-off-by: Ondrej Jirman <megous@xxxxxxxxxx>
> > Cc: Hans de Goede <hdegoede@xxxxxxxxxx>
>
> Should this go to stable?
Without this patch, VBUS is not turned off when I disconnect a hub from the
Type-C port (because fusb302 will not notice the disconnect), and it stays on
until next plugin of some device, say a normal non PD charger.
So I guess for a brief period you can have both sides provide VBUS (until
fusb302/tcpm processes the next plugin). It may be a problem if VBUS was more
than 5V (not very likely for devices running this driver, I guess).
regards,
o.
> Acked-by: Heikki Krogerus@xxxxxxxxxxxxxxx
>
> > ---
> > drivers/usb/typec/tcpm/fusb302.c | 6 ++++--
> > 1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/usb/typec/tcpm/fusb302.c b/drivers/usb/typec/tcpm/fusb302.c
> > index 7a2a17866a823..72f9001b07921 100644
> > --- a/drivers/usb/typec/tcpm/fusb302.c
> > +++ b/drivers/usb/typec/tcpm/fusb302.c
> > @@ -669,25 +669,27 @@ static int tcpm_set_cc(struct tcpc_dev *dev, enum typec_cc_status cc)
> > ret = fusb302_i2c_mask_write(chip, FUSB_REG_MASK,
> > FUSB_REG_MASK_BC_LVL |
> > FUSB_REG_MASK_COMP_CHNG,
> > - FUSB_REG_MASK_COMP_CHNG);
> > + FUSB_REG_MASK_BC_LVL);
> > if (ret < 0) {
> > fusb302_log(chip, "cannot set SRC interrupt, ret=%d",
> > ret);
> > goto done;
> > }
> > chip->intr_comp_chng = true;
> > + chip->intr_bc_lvl = false;
> > break;
> > case TYPEC_CC_RD:
> > ret = fusb302_i2c_mask_write(chip, FUSB_REG_MASK,
> > FUSB_REG_MASK_BC_LVL |
> > FUSB_REG_MASK_COMP_CHNG,
> > - FUSB_REG_MASK_BC_LVL);
> > + FUSB_REG_MASK_COMP_CHNG);
> > if (ret < 0) {
> > fusb302_log(chip, "cannot set SRC interrupt, ret=%d",
> > ret);
> > goto done;
> > }
> > chip->intr_bc_lvl = true;
> > + chip->intr_comp_chng = false;
> > break;
> > default:
> > break;
>
> thanks,
>
> --
> heikki
