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Subject: Re: [Patch V2 04/18] phy: tegra: xusb: Add usb-phy support
To:     Thierry Reding <thierry.reding@gmail.com>
CC:     <balbi@kernel.org>, <gregkh@linuxfoundation.org>,
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References: <1576660591-10383-1-git-send-email-nkristam@nvidia.com>
 <1576660591-10383-5-git-send-email-nkristam@nvidia.com>
 <20191219133707.GK1440537@ulmo>
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From:   Nagarjuna Kristam <nkristam@nvidia.com>
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Date:   Fri, 27 Dec 2019 12:36:05 +0530
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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@nvidia.com>
>> ---
>> 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