Re: [PATCH 2/3] usbtouchscreen: Implement runtime power management

On Mon, Jun 07, 2010 at 10:47:33PM +0200, Oliver Neukum wrote:

Am Montag, 7. Juni 2010 22:22:54 schrieb Alan Stern:

quoted

On Mon, 7 Jun 2010, Oliver Neukum wrote:

quoted

Am Montag, 7. Juni 2010 18:23:16 schrieb Dmitry Torokhov:

quoted

On Mon, Jun 07, 2010 at 03:13:42PM +0200, Oliver Neukum wrote:

quoted

 static int usbtouch_open(struct input_dev *input)
 {
 	struct usbtouch_usb *usbtouch = input_get_drvdata(input);
+	int r;
 
 	usbtouch->irq->dev = interface_to_usbdev(usbtouch->interface);
 
+	r = usb_autopm_get_interface(usbtouch->interface) ? -EIO : 0;

Why are we clobbering error code with -EIO? We should propagate te code
returned to us (here and below).

usb_autopm_get_interface() uses internal USB error codes which with
a few exceptions, do not have the meaning error codes in user space
have.

But other drivers don't do this.  What's special about usbtouch?

Then I'd say the other drivers are wrong. We cannot leak USB specific
codes. Maybe we should pass -ENOMEM and -ENODEV, but the others
really don't mean anything as generic codes.

No, I'd say that usb_autopm_get_interface() is wrong - since it is
supposed to be used by drivers who are not concerned about USB-specific
codes these functions should not leak them to the callers but rather
provide ones suitable for reporting upstream.

Thanks.

-- 
Dmitry
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