From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2474DC06510 for ; Tue, 2 Jul 2019 14:29:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0464521479 for ; Tue, 2 Jul 2019 14:29:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726686AbfGBO3p (ORCPT ); Tue, 2 Jul 2019 10:29:45 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:48442 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1726341AbfGBO3p (ORCPT ); Tue, 2 Jul 2019 10:29:45 -0400 Received: (qmail 2917 invoked by uid 2102); 2 Jul 2019 10:29:44 -0400 Received: from localhost (sendmail-bs@127.0.0.1) by localhost with SMTP; 2 Jul 2019 10:29:44 -0400 Date: Tue, 2 Jul 2019 10:29:44 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Oliver Neukum cc: Greg KH , Mayuresh Kulkarni , , USB list Subject: Re: [PATCH] usb: core: devio: add ioctls for suspend and resume In-Reply-To: <1562059312.5819.11.camel@suse.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Tue, 2 Jul 2019, Oliver Neukum wrote: > Am Montag, den 01.07.2019, 10:17 -0400 schrieb Alan Stern: > > On Mon, 1 Jul 2019, Oliver Neukum wrote: > > > > > Am Donnerstag, den 27.06.2019, 09:52 -0400 schrieb Alan Stern: > > > > > > > > > > > Or maybe the WAIT_FOR_RESUME ioctl returns because there was a remote > > > > wakeup. In this case also you would call FORBID_SUSPEND. > > > > > > > > In fact, you should call FORBID_SUSPEND _whenever_ WAIT_FOR_RESUME > > > > > > Well, this kind of indicates that the original syscall should bump > > > the counter. > > > > Perhaps it does, but... > > > > > > returns, unless your program has decided not to use the device any more > > > > (in which case you don't care whether the device is suspended or > > > > resumed). > > > > > > Then you should close the device. > > > > Exactly. Suppose WAIT_FOR_RESUME is interrupted and then the program > > closes the device. There's no need to force the device back to full > > power in this situation. > > But that is the error case. You return an error code. The point of that > is to report that a syscall did not have all requested effects. Okay, I can change the patch to work as you suggest. The WAIT_FOR_RESUME ioctl will do the equivalent of FORBID_SUSPEND whenever it returns with no error. Alan Stern