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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 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 D7CE9C06510 for ; Tue, 2 Jul 2019 09:35:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B5A2E20659 for ; Tue, 2 Jul 2019 09:35:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726963AbfGBJfp (ORCPT ); Tue, 2 Jul 2019 05:35:45 -0400 Received: from mx2.suse.de ([195.135.220.15]:52504 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726861AbfGBJfo (ORCPT ); Tue, 2 Jul 2019 05:35:44 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id C3F08AC9B; Tue, 2 Jul 2019 09:35:43 +0000 (UTC) Message-ID: <1562059312.5819.11.camel@suse.com> Subject: Re: [PATCH] usb: core: devio: add ioctls for suspend and resume From: Oliver Neukum To: Alan Stern Cc: Greg KH , Mayuresh Kulkarni , patches@opensource.cirrus.com, USB list Date: Tue, 02 Jul 2019 11:21:52 +0200 In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.26.6 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org 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. Regards Oliver