Re: [PATCH v4 4/4] phy: add phy-hi6220-usb

From: zhangfei
Date: Sat Feb 21 2015 - 10:03:25 EST

Hi, Balbi

On 02/21/2015 12:06 AM, Felipe Balbi wrote:

On Fri, Feb 20, 2015 at 11:44:37PM +0800, zhangfei wrote:
Hi, Balbi

On 02/20/2015 10:41 PM, Felipe Balbi wrote:

+static void hi6220_start_peripheral(struct hi6220_priv *priv, bool on)
+ struct usb_otg *otg = priv->phy.otg;
+ if (!otg->gadget)
+ return;
+ if (on)
+ usb_gadget_connect(otg->gadget);
+ else
+ usb_gadget_disconnect(otg->gadget);

why is the PHY fiddling with pullups ?

We use this to enable/disable otg gadget mode.

I got that, but the pullups don't belong to the PHY, they belong to the

The gpio_id & gpio_vbus are used to distinguish otg gadget mode or
host mode.
When micro usb or otg device attached to otg, gpio_vbus falling down.
And gpio_id = 1 is micro usb, gpio_id = 0 is otg device.

all of that I understood clearly :-)

So when micro usb attached, we enable gadget mode; while micro usb
detached, we disable gadget mode, and dwc2 will automatically set to
host mode.

that's all fine, I'm concerned about letting the PHY fiddle with
something it doesn't own. If I am to change pullups rules in udc-core,
this is likely to break down miserably and I don't want to have to go
through that.

Thanks for the clarifying.

How about using usb_gadget_vbus_connect/disconnect, which are used in many files under drivers/usb/phy.
There is no vbus_session in dwc2/gadget.c, I thought it would be same as pullup.

However, usb_gadget_vbus_connect still need para gadget, where should we put this file, drivers/usb/phy or drivers/phy

+static void hi6220_detect_work(struct work_struct *work)
+ struct hi6220_priv *priv =
+ container_of(work, struct hi6220_priv,;
+ int gpio_id, gpio_vbus;
+ enum usb_otg_state state;
+ if (!gpio_is_valid(priv->gpio_id) || !gpio_is_valid(priv->gpio_vbus))
+ return;
+ gpio_id = gpio_get_value_cansleep(priv->gpio_id);
+ gpio_vbus = gpio_get_value_cansleep(priv->gpio_vbus);

looks like this should be using extcon
Not used extcon before.
However, we need gpio_vbus interrupt.
Checked phy-tahvo.c and phy-omap-otg.c, not find extcon related with
Will investigate tomorrow.

I think there is no need to use extcon, gpio is clear enough.
extcon-gpio.c even do not support dt.

+ if (gpio_vbus == 0) {
+ if (gpio_id == 1)
+ else
+ state = OTG_STATE_A_HOST;
+ } else {
+ state = OTG_STATE_A_HOST;
+ }
+ if (priv->state != state) {
+ hi6220_start_peripheral(priv, state == OTG_STATE_B_PERIPHERAL);
+ priv->state = state;
+ }
+static irqreturn_t hiusb_gpio_intr(int irq, void *data)
+ struct hi6220_priv *priv = (struct hi6220_priv *)data;
+ /* add debounce time */
+ schedule_delayed_work(&priv->work, msecs_to_jiffies(100));

this is really bad. We have threaded interrupt support, right ?

Since we use two gpio to distinguish gadget mode or host mode.
Debounce time can introduce more accuracy.

gpio_set_debounce() ?
Not all gpio.c support set_debounce, including gpio-pl061.c.

I think threaded interrupt can not be used for adding debounce time.
Here add debounce is just for safety.

add the debounce to the gpio itself.

Here the debounce added only for safety.
gpio_id may mis-report when unplug usb, but it is correct for plug usb & otg device.
So debounce can be omitted.
If you think using delayed work for debounce is ugly, it is fine switch to threaded_irq.


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