Re: [rft]power management for usbtouch

[Oliver Neukum <oliver-GvhC2dPhHPQdnm+yROfE0A@public.gmane.org>]

Am Donnerstag 26 Juni 2008 16:45:45 schrieb Ville Syrjälä:
> On Thu, Jun 26, 2008 at 03:57:17PM +0200, Oliver Neukum wrote:
> > Hi,
> > 
> > this is power management for usbtouch. Could somebody test it?
> > 
> > 	Regards
> > 		Oliver
> > 
> > ---
> > 
> > --- linux-2.6.26-sierra/drivers/input/touchscreen/usbtouchscreen.c.alt2	2008-06-26 15:23:38.000000000 +0200
> > +++ linux-2.6.26-sierra/drivers/input/touchscreen/usbtouchscreen.c	2008-06-26 15:48:44.000000000 +0200
> > @@ -89,13 +89,17 @@ struct usbtouch_usb {
> >  	int buf_len;
> >  	struct urb *irq;
> >  	struct usb_device *udev;
> > +	struct usb_interface *intf;
> >  	struct input_dev *input;
> >  	struct usbtouch_device_info *type;
> > +	struct mutex lock;
> >  	char name[128];
> >  	char phys[64];
> >  
> >  	int x, y;
> >  	int touch, press;
> > +
> > +	char open:1;
> >  };
> >  
> >  
> > @@ -820,13 +824,23 @@ exit:
> >  static int usbtouch_open(struct input_dev *input)
> >  {
> >  	struct usbtouch_usb *usbtouch = input_get_drvdata(input);
> > +	int rv;
> >  
> > +	rv = usb_autopm_get_interface(usbtouch->intf);
> > +	if (rv < 0)
> > +		goto bail;
> > +	mutex_lock(&usbtouch->lock);
> >  	usbtouch->irq->dev = usbtouch->udev;
> >  
> > -	if (usb_submit_urb(usbtouch->irq, GFP_KERNEL))
> > -		return -EIO;
> > -
> > -	return 0;
> > +	if (usb_submit_urb(usbtouch->irq, GFP_KERNEL)) {
> > +		rv = -EIO;
> > +		usb_autopm_put_interface(usbtouch->intf);
> > +	} else {
> > +		usbtouch->open = 1;
> > +	}
> > +	mutex_unlock(&usbtouch->lock);
> > +bail:
> > +	return rv;
> >  }
> >  
> >  static void usbtouch_close(struct input_dev *input)
> > @@ -834,6 +848,10 @@ static void usbtouch_close(struct input_
> >  	struct usbtouch_usb *usbtouch = input_get_drvdata(input);
> >  
> >  	usb_kill_urb(usbtouch->irq);
> 
> If usbtouch_resume() happens here it will resubmit the urb.

Thanks. That's a bug.

> > +	mutex_lock(&usbtouch->lock);
> > +	usbtouch->open = 0;
> > +	mutex_unlock(&usbtouch->lock);
> > +	usb_autopm_put_interface(usbtouch->intf);
> >  }
> >  
> >  
> > @@ -889,6 +907,8 @@ static int usbtouch_probe(struct usb_int
> >  
> >  	usbtouch->udev = udev;
> >  	usbtouch->input = input_dev;
> > +	mutex_init(&usbtouch->lock);
> > +	usbtouch->intf = intf;
> >  
> >  	if (udev->manufacturer)
> >  		strlcpy(usbtouch->name, udev->manufacturer, sizeof(usbtouch->name));
> > @@ -973,20 +993,76 @@ static void usbtouch_disconnect(struct u
> >  
> >  	dbg("%s - usbtouch is initialized, cleaning up", __FUNCTION__);
> >  	usb_set_intfdata(intf, NULL);
> > -	input_unregister_device(usbtouch->input);
> >  	usb_kill_urb(usbtouch->irq);
> > +	input_unregister_device(usbtouch->input);
> >  	usb_free_urb(usbtouch->irq);
> >  	usbtouch_free_buffers(interface_to_usbdev(intf), usbtouch);
> >  	kfree(usbtouch);
> >  }
> 
> Already discussed :)

OK.

> > +static int usbtouch_suspend(struct usb_interface *intf, pm_message_t message)
> > +{
> > +	struct usbtouch_usb *usbtouch = usb_get_intfdata(intf);
> > +
> > +	dbg("%s - called", __FUNCTION__);
> > +
> > +	mutex_lock(&usbtouch->lock);
> > +	usb_kill_urb(usbtouch->irq);
> > +	mutex_unlock(&usbtouch->lock);
> > +	return 0;
> > +}
> 
> Shouldn't all the usb_kill_urb() callers check the usbtouch->open flag
> first? Perhaps it's not considered an error to kill an unsubmitted urb
> though.

It's no problem to call usb_kill_urb() on an unsubmitted urb.
That must be the case as the urb can always finish.

> > +static int usbtouch_resume(struct usb_interface *intf)
> > +{
> > +	struct usbtouch_usb *usbtouch = usb_get_intfdata(intf);
> > +	int rv = 0;
> > +
> > +	dbg("%s - called", __FUNCTION__);
> > +
> > +	mutex_lock(&usbtouch->lock);
> > +	if (usbtouch->open)
> > +		rv = usb_submit_urb(usbtouch->irq, GFP_NOIO);
> > +	mutex_unlock(&usbtouch->lock);
> > +	return rv;
> > +}
> > +
> > +static int usbtouch_pre_reset(struct usb_interface *intf)
> > +{
> > +	struct usbtouch_usb *usbtouch = usb_get_intfdata(intf);
> > +
> > +	dbg("%s - called", __FUNCTION__);
> > +
> > +	mutex_lock(&usbtouch->lock);
> > +	usb_kill_urb(usbtouch->irq);
> > +	return 0;
> > +}
> > +
> > +static int usbtouch_post_reset(struct usb_interface *intf)
> > +{
> > +	struct usbtouch_usb *usbtouch = usb_get_intfdata(intf);
> > +	int rv = 0;
> > +
> > +	dbg("%s - called", __FUNCTION__);
> > +
> > +	if (usbtouch->open)
> > +		rv = usb_submit_urb(usbtouch->irq, GFP_NOIO);
> > +	mutex_unlock(&usbtouch->lock);
> > +	return rv;
> > +}
> 
> Hmm. Are pre_reset and post_reset actually required in such simple cases?
> AFAICS device reset is already protected against pm and autopm. Or is
> resubmitting urbs necessary after a reset? I'm mainly interested since
> I didn't implement these callbacks in my ati_remote2 patch.

If somebody resets the device you can assume it was in a bad shape.
It's much safer to cleanly resubmit.

> >  MODULE_DEVICE_TABLE(usb, usbtouch_devices);
> >  
> >  static struct usb_driver usbtouch_driver = {
> >  	.name		= "usbtouchscreen",
> >  	.probe		= usbtouch_probe,
> >  	.disconnect	= usbtouch_disconnect,
> > +	.suspend	= usbtouch_suspend,
> > +	.resume		= usbtouch_resume,
> > +	.reset_resume	= usbtouch_resume,
> 
> What is the purpose of providing identical resume and reset_resume?
> AFAICS reset_resume is only called if USB_QUIRK_RESET_RESUME is
> enabled.

It is also called if you resume from STD if power was lost.

	Regards
		Oliver
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