From: Oliver Neukum <oliver@neukum.org>
To: Greg KH <greg@kroah.com>
Subject: Re: [RFC] USB: driver for iphone charging
Date: Fri, 24 Aug 2007 09:20:46 +0200
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Cc: linux-kernel@vger.kernel.org, linux-usb-devel@lists.sourceforge.net,
       Matt Colyer <matt@colyer.name>, jeffm@suse.de
References: <20070823224514.GA25830@kroah.com>
In-Reply-To: <20070823224514.GA25830@kroah.com>
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Am Freitag 24 August 2007 schrieb Greg KH:

Hi,

> +static int select_configuration(struct usb_device *udev)
> +{
> +???????char *dummy_buffer = kzalloc(2, GFP_KERNEL);
> +???????int retval;
> +
> +???????if (!dummy_buffer)
> +???????????????return -ENOMEM;
> +
> +???????dbg(&udev->dev, "Calling set_configuration\n");
> +???????retval = usb_driver_set_configuration(udev, 3);
> +???????if (retval) {
> +???????????????dev_err(&udev->dev, "Set Configuration failed :%d.\n", retval);
> +???????????????goto exit;
> +???????}
> +
> +???????dbg(&udev->dev, "Sending first magic command\n");
> +???????retval = usb_control_msg(udev, usb_sndctrlpipe(udev, 0), 0x40, 0x40,
> +??????????????????????????????? 0x6400, 0, dummy_buffer, 0, 100);
> +

int usb_driver_set_configuration(struct usb_device *udev, int config)
{
	struct set_config_request *req;

	req = kmalloc(sizeof(*req), GFP_KERNEL);
	if (!req)
		return -ENOMEM;
	req->udev = udev;
	req->config = config;
	INIT_WORK(&req->work, driver_set_config_work);

	usb_get_dev(udev);
	schedule_work(&req->work);
	return 0;
}

This schedules the change via a workqueue, so you'll be reprobed. If you
fire of the first vendor command you are doing so before the configuration
is changed. How is this supposed to work?

	Regards
		Oliver
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