RE: [PATCH v5] usb: ohci-at91: Forcibly suspend ports while USB suspend

[Wenyou.Yang]

Hi Alan,

> -----Original Message-----
> From: Alan Stern [mailto:stern@xxxxxxxxxxxxxxxxxxx]
> Sent: 2016年8月4日 23:02
> To: Wenyou Yang <wenyou.yang@xxxxxxxxx>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>; Nicolas Ferre
> <nicolas.ferre@xxxxxxxxx>; Alexandre Belloni <alexandre.belloni@free-
> electrons.com>; linux-kernel@xxxxxxxxxxxxxxx; linux-arm-
> kernel@xxxxxxxxxxxxxxxxxxx; linux-usb@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v5] usb: ohci-at91: Forcibly suspend ports while USB
> suspend
> 
> On Thu, 4 Aug 2016, Wenyou Yang wrote:
> 
> > The usb controller does not managed correctly the suspend mode for the
> > ehci. In echi mode, there is no way to have utmi_suspend_o_n[1]
> > suspend without any device connected to it. This is why this specific
> > control is added to fix this issue. The suspend mode works in ohci
> > mode.
> 
> Why are you talking about EHCI mode?  This patch is only for the
> ohci-at91 driver.

Actually I described the issue according to the documents from our IP,
and this specific control is recommended to do in ohci mode.

> 
> > This specific control is by setting the SUSPEND_A/B/C fields of
> > SFR_OHCIICR(OHCI Interrupt Configuration Register) in the SFR while
> > OHCI USB suspend.
> >
> > This setting operation must be done before the USB clock disabled,
> > clear them after the USB clock enabled.
> >
> > Signed-off-by: Wenyou Yang <wenyou.yang@xxxxxxxxx>
> > Reviewed-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx>
> > Acked-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx>
> 
> I don't know if this is any better than before!  See the comments below.

Yes, I think so.

What else advice?

> 
> > ---
> >
> > Changes in v5:
> >  - Use the USB_PORT_FEAT_SUSPEND subcase of the SetPortFeature case
> >    to take care it.
> >  - Update the commit log.
> >
> > Changes in v4:
> >  - To check whether the SFR node with "atmel,sama5d2-sfr" compatible
> >    is present or not to decide if this feature is applied or not
> >    when USB OHCI suspend/resume, instead of new compatible.
> >  - Drop the compatible "atmel,sama5d2-ohci".
> >  - Drop [PATCH 2/2] ARM: at91/dt: sama5d2: Use new compatible for
> >    ohci node.
> >  - Drop include/soc/at91/at91_sfr.h, move the macro definitions to
> >    atmel-sfr.h which already exists.
> >  - Change the defines to align the exists.
> >
> > Changes in v3:
> >  - Change the compatible description for more precise.
> >
> > Changes in v2:
> >  - Add compatible to support forcibly suspend the ports.
> >  - Add soc/at91/at91_sfr.h to accommodate the defines.
> >  - Add error checking for .sfr_regmap.
> >  - Remove unnecessary regmap_read() statement.
> 
> 
> > @@ -282,6 +301,28 @@ static int ohci_at91_hub_status_data(struct usb_hcd
> *hcd, char *buf)
> >  	return length;
> >  }
> >
> > +static int ohci_at91_port_ctrl(struct regmap *regmap, u16 port, u8
> > +set) {
> > +	u32 regval;
> > +	int ret;
> > +
> > +	if (!regmap)
> > +		return 0;
> > +
> > +	ret = regmap_read(regmap, AT91_SFR_OHCIICR, &regval);
> > +	if (ret)
> > +		return ret;
> > +
> > +	if (set)
> > +		regval |= AT91_OHCIICR_SUSPEND(port);
> > +	else
> > +		regval &= ~AT91_OHCIICR_SUSPEND(port);
> 
> In the earlier versions of this patch, you did not use the port number.
> Why has this changed?

This function is called by ohci_at91_hub_control(), which is invoked on basis of port number.

So, I think it is more reasonable of adding the port argument. 

> 
> How many ports does this controller have?

This controller has three ports.

> 
> > +
> > +	regmap_write(regmap, AT91_SFR_OHCIICR, regval);
> > +
> > +	return 0;
> > +}
> > +
> >  /*
> >   * Look at the control requests to the root hub and see if we need to override.
> >   */
> > @@ -289,6 +330,7 @@ static int ohci_at91_hub_control(struct usb_hcd *hcd,
> u16 typeReq, u16 wValue,
> >  				 u16 wIndex, char *buf, u16 wLength)  {
> >  	struct at91_usbh_data *pdata =
> > dev_get_platdata(hcd->self.controller);
> > +	struct ohci_at91_priv *ohci_at91 = hcd_to_ohci_at91_priv(hcd);
> >  	struct usb_hub_descriptor *desc;
> >  	int ret = -EINVAL;
> >  	u32 *data = (u32 *)buf;
> > @@ -301,7 +343,8 @@ static int ohci_at91_hub_control(struct usb_hcd
> > *hcd, u16 typeReq, u16 wValue,
> >
> >  	switch (typeReq) {
> >  	case SetPortFeature:
> > -		if (wValue == USB_PORT_FEAT_POWER) {
> > +		switch (wValue) {
> > +		case USB_PORT_FEAT_POWER:
> >  			dev_dbg(hcd->self.controller, "SetPortFeat: POWER\n");
> >  			if (valid_port(wIndex)) {
> >  				ohci_at91_usb_set_power(pdata, wIndex, 1); @@
> -309,6 +352,11 @@
> > static int ohci_at91_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
> >  			}
> >
> >  			goto out;
> > +
> > +		case USB_PORT_FEAT_SUSPEND:
> > +			dev_dbg(hcd->self.controller, "SetPortFeat: SUSPEND\n");
> > +			ohci_at91_port_ctrl(ohci_at91->sfr_regmap, wIndex, 1);
> > +			break;
> >  		}
> >  		break;
> >
> > @@ -342,6 +390,12 @@ static int ohci_at91_hub_control(struct usb_hcd *hcd,
> u16 typeReq, u16 wValue,
> >  				ohci_at91_usb_set_power(pdata, wIndex, 0);
> >  				return 0;
> >  			}
> > +			break;
> > +
> > +		case USB_PORT_FEAT_SUSPEND:
> > +			dev_dbg(hcd->self.controller, "ClearPortFeature:
> SUSPEND\n");
> > +			ohci_at91_port_ctrl(ohci_at91->sfr_regmap, wIndex, 0);
> > +			break;
> >  		}
> >  		break;
> >  	}
> 
> Note that after all this, the code goes ahead to call ohci_bub_control().

Yes, 
The ohci_bub_control() will change the port_status[port] register after this operation.

> 
> > @@ -587,7 +641,8 @@ ohci_hcd_at91_drv_suspend(struct device *dev)
> >  	struct usb_hcd	*hcd = dev_get_drvdata(dev);
> >  	struct ohci_hcd	*ohci = hcd_to_ohci(hcd);
> >  	struct ohci_at91_priv *ohci_at91 = hcd_to_ohci_at91_priv(hcd);
> > -	int		ret;
> > +	u16 i;
> > +	int ret;
> >
> >  	/*
> >  	 * Disable wakeup if we are going to sleep with slow clock mode @@
> > -599,6 +654,11 @@ ohci_hcd_at91_drv_suspend(struct device *dev)
> >  	if (ohci_at91->wakeup)
> >  		enable_irq_wake(hcd->irq);
> >
> > +	for (i = 0; i < ohci->num_ports; i++) {
> > +		ohci_at91_hub_control(hcd, SetPortFeature,
> > +				      USB_PORT_FEAT_SUSPEND, (i + 1), NULL,
> 0);
> > +	}
> > +
> >  	ret = ohci_suspend(hcd, ohci_at91->wakeup);
> 
> Do you really want to call ohci_hub_control() for ports that don't have a device
> attached?

Yes. I need to do this operation for ports that don't have a device attached.

> 
> >  	if (ret) {
> >  		if (ohci_at91->wakeup)
> > @@ -630,7 +690,9 @@ static int __maybe_unused
> > ohci_hcd_at91_drv_resume(struct device *dev)  {
> >  	struct usb_hcd	*hcd = dev_get_drvdata(dev);
> > +	struct ohci_hcd	*ohci = hcd_to_ohci(hcd);
> >  	struct ohci_at91_priv *ohci_at91 = hcd_to_ohci_at91_priv(hcd);
> > +	u16 i;
> >
> >  	if (ohci_at91->wakeup)
> >  		disable_irq_wake(hcd->irq);
> > @@ -638,6 +700,12 @@ ohci_hcd_at91_drv_resume(struct device *dev)
> >  	at91_start_clock(ohci_at91);
> >
> >  	ohci_resume(hcd, false);
> > +
> > +	for (i = 0; i < ohci->num_ports; i++) {
> > +		ohci_at91_hub_control(hcd, ClearPortFeature,
> > +				      USB_PORT_FEAT_SUSPEND, i + 1, NULL,
> 0);
> > +	}
> 
> Have you thought about how this will interact with runtime PM?
> 
> If you intend to do this only for system suspend and not for runtime suspend, why
> not set all the suspend bits for all the ports in the OHCIICR register at once, in a
> single write, like you were doing before?

Yes, this is only for system suspend. 

As I mentioned above, here calls ohci_at91_hub_control(), which is based on port number.

> 
> Alan Stern


Best Regards,
Wenyou Yang