RE: [PATCH 3/3] usb: typec: ucsi: retry find role swithch when module load late

["Linyu Yuan (QUIC)" <quic_linyyuan@quicinc.com>]

> From: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> Sent: Wednesday, April 13, 2022 3:46 PM
> To: Linyu Yuan (QUIC) <quic_linyyuan@quicinc.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>; linux-
> usb@vger.kernel.org; Jack Pham (QUIC) <quic_jackp@quicinc.com>
> 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@quicinc.com>
> > ---
> >  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.
> 
> thanks,
> 
> --
> heikki