Re: [Patch V2 04/18] phy: tegra: xusb: Add usb-phy support

[Nagarjuna Kristam]

On 19-12-2019 19:07, Thierry Reding wrote:
> On Wed, Dec 18, 2019 at 02:46:17PM +0530, Nagarjuna Kristam wrote:
> > For USB 2 ports that has usb-role-switch enabled, add usb-phy for
> > corresponding USB 2 phy. USB role changes from role switch are then
> > updated to corresponding host and device mode drivers via usb-phy notifier
> > block.
> >
> > Signed-off-by: Nagarjuna Kristam<nkristam@xxxxxxxxxx>
> > ---
> > V2:
> >   - Added dev_set_drvdata for port->dev.
> > ---
> >   drivers/phy/tegra/xusb.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++++
> >   drivers/phy/tegra/xusb.h |  2 ++
> >   2 files changed, 73 insertions(+)
> >
> > diff --git a/drivers/phy/tegra/xusb.c b/drivers/phy/tegra/xusb.c
> > index dc00b42..5bde8f1 100644
> > --- a/drivers/phy/tegra/xusb.c
> > +++ b/drivers/phy/tegra/xusb.c
> > @@ -533,6 +533,8 @@ static int tegra_xusb_port_init(struct tegra_xusb_port *port,
> >   	if (err < 0)
> >   		goto unregister;
> >   
> > +	dev_set_drvdata(&port->dev, port);
> > +
> >   	return 0;
> >   
> >   unregister:
> > @@ -545,6 +547,8 @@ static void tegra_xusb_port_unregister(struct tegra_xusb_port *port)
> >   	if (!IS_ERR_OR_NULL(port->usb_role_sw)) {
> >   		of_platform_depopulate(&port->dev);
> >   		usb_role_switch_unregister(port->usb_role_sw);
> > +		cancel_work_sync(&port->usb_phy_work);
> > +		usb_remove_phy(&port->usb_phy);
> >   	}
> >   	device_unregister(&port->dev);
> >   }
> > @@ -556,16 +560,59 @@ static const char *const modes[] = {
> >   	[USB_DR_MODE_OTG] = "otg",
> >   };
> >   
> > +static void tegra_xusb_usb_phy_work(struct work_struct *work)
> > +{
> > +	struct tegra_xusb_port *port = container_of(work,
> > +				struct tegra_xusb_port, usb_phy_work);
> Perhaps add a static inline function to cast this? Might not be worth it
> since we only need to cast once. In that case, perhaps make this look a
> little prettier by aligning arguments on subsequent lines with "work" on
> the first line?
Will align arguments with "work".

> > +	enum usb_role role = usb_role_switch_get_role(port->usb_role_sw);
> > +
> > +	dev_dbg(&port->dev, "%s calling notifier for role %d\n", __func__,
> > +		role);
> > +
> > +	atomic_notifier_call_chain(&port->usb_phy.notifier, role,
> > +				   &port->usb_phy);
> I'm curious: you use an atomic notifier call chain here but then you
> schedule work to call it. Typically you only need to schedule work if
> you get notified in atomic context and you need to process the event
> outside of the atomic context.
>
> Since these are atomic notifiers, do we really need the work? Or the
> other way around: why not use regular notifiers if we're processing them
> from non-atomic contexts only anyway?
notifier used by usb-phy are atomic notifiers and hence need to call
atomic_notifier_call_chain only in this context., regular notifiers
cannot be used.

> > +}
> > +
> >   static int tegra_xusb_role_sw_set(struct device *dev, enum usb_role role)
> >   {
> > +	struct tegra_xusb_port *port = dev_get_drvdata(dev);
> > +
> >   	dev_dbg(dev, "%s calling notifier for role is %d\n", __func__, role);
> >   
> > +	schedule_work(&port->usb_phy_work);
> > +
> > +	return 0;
> > +}
> > +
> > +static int tegra_xusb_set_peripheral(struct usb_otg *otg,
> > +					struct usb_gadget *gadget)
> > +{
> > +	struct tegra_xusb_port *port = container_of(otg->usb_phy,
> > +					struct tegra_xusb_port, usb_phy);
> > +
> > +	if (gadget != NULL)
> > +		schedule_work(&port->usb_phy_work);
> > +
> > +	return 0;
> > +}
> > +
> > +static int tegra_xusb_set_host(struct usb_otg *otg, struct usb_bus *host)
> > +{
> > +	struct tegra_xusb_port *port = container_of(otg->usb_phy,
> > +					struct tegra_xusb_port, usb_phy);
> > +
> > +	if (host != NULL)
> > +		schedule_work(&port->usb_phy_work);
> > +
> >   	return 0;
> >   }
> >   
> > +
> >   static int tegra_xusb_setup_usb_role_switch(struct tegra_xusb_port *port)
> >   {
> >   	int err = 0;
> > +	struct tegra_xusb_lane *lane = tegra_xusb_find_lane(port->padctl,
> > +							"usb2", port->index);
> You're not properly aligning the arguments here.
>
> Thierry
Will align here and other places accordingly.

-Nagarjuna
> >   	struct usb_role_switch_desc role_sx_desc = {
> >   					.set = tegra_xusb_role_sw_set,
> >   					.fwnode = dev_fwnode(&port->dev),
> > @@ -578,6 +625,30 @@ static int tegra_xusb_setup_usb_role_switch(struct tegra_xusb_port *port)
> >   		if (err != EPROBE_DEFER)
> >   			dev_err(&port->dev, "Failed to register USB role SW: %d",
> >   				err);
> > +		return err;
> > +	}
> > +
> > +	INIT_WORK(&port->usb_phy_work, tegra_xusb_usb_phy_work);
> > +
> > +	port->usb_phy.otg = devm_kzalloc(&port->dev,
> > +					 sizeof(struct usb_otg), GFP_KERNEL);
> > +	if (!port->usb_phy.otg)
> > +		return -ENOMEM;
> > +
> > +	/*
> > +	 * Assign phy dev to usb-phy dev. Host/device drivers can use phy
> > +	 * reference to retrieve usb-phy details.
> > +	 */
> > +	port->usb_phy.dev = &lane->pad->lanes[port->index]->dev;
> > +	port->usb_phy.dev->driver = port->padctl->dev->driver;
> > +	port->usb_phy.otg->usb_phy = &port->usb_phy;
> > +	port->usb_phy.otg->set_peripheral = tegra_xusb_set_peripheral;
> > +	port->usb_phy.otg->set_host = tegra_xusb_set_host;
> > +
> > +	err = usb_add_phy_dev(&port->usb_phy);
> > +	if (err < 0) {
> > +		dev_err(&port->dev, "Failed to add usbphy: %d\n", err);
> > +		return err;
> >   	}
> >   
> >   	/* populate connector entry */
> > diff --git a/drivers/phy/tegra/xusb.h b/drivers/phy/tegra/xusb.h
> > index 9f27899..2345657 100644
> > --- a/drivers/phy/tegra/xusb.h
> > +++ b/drivers/phy/tegra/xusb.h
> > @@ -268,6 +268,8 @@ struct tegra_xusb_port {
> >   	struct device dev;
> >   
> >   	struct usb_role_switch *usb_role_sw;
> > +	struct work_struct usb_phy_work;
> > +	struct usb_phy usb_phy;
> >   
> >   	const struct tegra_xusb_port_ops *ops;
> >   };
> > --
> > 2.7.4