RE: [PATCH v3 4/4] 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 8:40 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 v3 4/4] usb: typec: ucsi: retry find role swithch when
> module load late
> 
> Hi,
> 
> You have to make the subject line a bit more clear. Perhaps you could
> just say "Wait for the USB role switches".

Sound great, will change once all discussion in this thread done.

> 
> On Wed, Apr 13, 2022 at 05:58:11PM +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 looks like you did not update that.

Sorry, will update later.

> 
> > It also means change ucsi init work to delayed_work.
> 
> So from where does that 100ms come from?

Yes, no place define it, just an experiment value.
Any suggestion ?

> 
> > Signed-off-by: Linyu Yuan <quic_linyyuan@quicinc.com>
> > ---
> > v2: keep original con->num in debug log
> > v3: change return value from -EAGAIN to PTR_ERR()
> >
> >  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 ce9192e..63c25dd 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",
> > +			con->num);
> > +		return PTR_ERR(con->usb_role_sw);
> > +	}
> > +
> >  	/* Delay other interactions with the con until registration is complete
> */
> >  	mutex_lock(&con->lock);
> >
> > @@ -1088,7 +1096,6 @@ static int ucsi_register_port(struct ucsi *ucsi, int
> index)
> >  	if (con->cap.op_mode &
> UCSI_CONCAP_OPMODE_DEBUG_ACCESSORY)
> >  		*accessory = TYPEC_ACCESSORY_DEBUG;
> >
> > -	cap->fwnode = ucsi_find_fwnode(con);
> >  	cap->driver_data = con;
> >  	cap->ops = &ucsi_ops;
> >
> > @@ -1147,13 +1154,6 @@ static int ucsi_register_port(struct ucsi *ucsi, int
> index)
> >  		ucsi_port_psy_changed(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",
> > -			con->num);
> > -		con->usb_role_sw = NULL;
> > -	}
> > -
> >  	/* Only notify USB controller if partner supports USB data */
> >  	if (!(UCSI_CONSTAT_PARTNER_FLAGS(con->status.flags) &
> UCSI_CONSTAT_PARTNER_FLAG_USB))
> >  		u_role = USB_ROLE_NONE;
> > @@ -1286,12 +1286,16 @@ static int ucsi_init(struct ucsi *ucsi)
> >
> >  static void ucsi_init_work(struct work_struct *work)
> >  {
> > -	struct ucsi *ucsi = container_of(work, struct ucsi, work);
> > +	struct ucsi *ucsi = container_of(work, struct ucsi, work.work);
> >  	int ret;
> >
> >  	ret = ucsi_init(ucsi);
> >  	if (ret)
> >  		dev_err(ucsi->dev, "PPM init failed (%d)\n", ret);
> > +
> > +
> 
> Extra line.
> 
> > +	if (ret == -EPROBE_DEFER)
> > +		queue_delayed_work(system_long_wq, &ucsi->work,
> HZ/10);
> 
> You have to stop queueing that eventually. You need a counter.
> 
> I'm still not sure why do you want to queue this same work again and
> again? Why not just call ucsi_init() in a loop?

Will follow your suggestion below.

> 
>         int my_counter = 1000;
So you prefer 10 second in total ?
If so, next version, I will change it to 500, as msleep(20), check next.
> 
>         while (ucsi_init(ucsi) == -EPROBE_DEFER && my_counter--)
>                 msleep(10);
In checkpatch.pl, it suggest msleep no less than 20ms each time.
msleep(20) ?

> 
> >  }

Great idea, it will be less code change.

> >
> >  /**
> > @@ -1331,7 +1335,7 @@ struct ucsi *ucsi_create(struct device *dev, const
> struct ucsi_operations *ops)
> >  	if (!ucsi)
> >  		return ERR_PTR(-ENOMEM);
> >
> > -	INIT_WORK(&ucsi->work, ucsi_init_work);
> > +	INIT_DELAYED_WORK(&ucsi->work, ucsi_init_work);
> >  	mutex_init(&ucsi->ppm_lock);
> >  	ucsi->dev = dev;
> >  	ucsi->ops = ops;
> > @@ -1366,7 +1370,7 @@ int ucsi_register(struct ucsi *ucsi)
> >  	if (!ucsi->version)
> >  		return -ENODEV;
> >
> > -	queue_work(system_long_wq, &ucsi->work);
> > +	queue_delayed_work(system_long_wq, &ucsi->work, 0);
> >
> >  	return 0;
> >  }
> > @@ -1383,7 +1387,7 @@ void ucsi_unregister(struct ucsi *ucsi)
> >  	u64 cmd = UCSI_SET_NOTIFICATION_ENABLE;
> >
> >  	/* Make sure that we are not in the middle of driver initialization */
> > -	cancel_work_sync(&ucsi->work);
> > +	cancel_delayed_work_sync(&ucsi->work);
> >
> >  	/* Disable notifications */
> >  	ucsi->ops->async_write(ucsi, UCSI_CONTROL, &cmd, sizeof(cmd));
> > diff --git a/drivers/usb/typec/ucsi/ucsi.h b/drivers/usb/typec/ucsi/ucsi.h
> > index 280f1e1..3812017 100644
> > --- a/drivers/usb/typec/ucsi/ucsi.h
> > +++ b/drivers/usb/typec/ucsi/ucsi.h
> > @@ -287,7 +287,7 @@ struct ucsi {
> >  	struct ucsi_capability cap;
> >  	struct ucsi_connector *connector;
> >
> > -	struct work_struct work;
> > +	struct delayed_work work;
> >
> >  	/* PPM Communication lock */
> >  	struct mutex ppm_lock;
> > --
> > 2.7.4
> 
> thanks,
> 
> --
> heikki