On Wed, Apr 13, 2022 at 08:00:35AM +0000, Linyu Yuan (QUIC) wrote:
> > From: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
> > Sent: Wednesday, April 13, 2022 3:46 PM
> > To: Linyu Yuan (QUIC) <quic_linyyuan@xxxxxxxxxxx>
> > Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>; linux-
> > usb@xxxxxxxxxxxxxxx; Jack Pham (QUIC) <quic_jackp@xxxxxxxxxxx>
> > Subject: Re: [PATCH 3/3] usb: typec: ucsi: retry find role swithch when
> > module load late
> >
> > On Tue, Apr 12, 2022 at 06:30:07PM +0800, Linyu Yuan wrote:
> > > When role switch enabled, return -EAGAIN if fail to find it due to
> > > module load ordering issue, then restart ucsi init work to find
> > > it again every 100ms.
> > >
> > > It also means change ucsi init work to delayed_work.
> > >
> > > Signed-off-by: Linyu Yuan <quic_linyyuan@xxxxxxxxxxx>
> > > ---
> > > drivers/usb/typec/ucsi/ucsi.c | 28 ++++++++++++++++------------
> > > drivers/usb/typec/ucsi/ucsi.h | 2 +-
> > > 2 files changed, 17 insertions(+), 13 deletions(-)
> > >
> > > diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
> > > index 684fc4f..fabd4df 100644
> > > --- a/drivers/usb/typec/ucsi/ucsi.c
> > > +++ b/drivers/usb/typec/ucsi/ucsi.c
> > > @@ -1053,6 +1053,14 @@ static int ucsi_register_port(struct ucsi *ucsi, int
> > index)
> > > con->num = index + 1;
> > > con->ucsi = ucsi;
> > >
> > > + cap->fwnode = ucsi_find_fwnode(con);
> > > + con->usb_role_sw = fwnode_usb_role_switch_get(cap->fwnode);
> > > + if (IS_ERR(con->usb_role_sw)) {
> > > + dev_err(ucsi->dev, "con%d: failed to get usb role switch\n",
> > > + index + 1);
> > > + return -EAGAIN;
> > > + }
> >
> > No, this is wrong. If there is a role switch assigned in the firmware
> > for the port, then fwnode_usb_role_switch_get() will return
> > -EPROBE_DEFER until the switch has been registered.
> >
> > So I think what you want to do is just make the failure to get the
> > role switch fatal in this driver. Just return PTR_ERR(con->usb_role_sw).
> Thanks, will change it to check -EPROBE_DEFER.
No, you don't check that, you just return that.
So you don't need that crazy polling mechanism where you queue a work
until you get the resource. Just let the driver core handle the
situation.
thanks,
--
heikki
