From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751518AbdAXIbI (ORCPT ); Tue, 24 Jan 2017 03:31:08 -0500 Received: from mx2.suse.de ([195.135.220.15]:35310 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751043AbdAXIbF (ORCPT ); Tue, 24 Jan 2017 03:31:05 -0500 Message-ID: <1485246651.12785.4.camel@suse.com> Subject: Re: [PATCH] USB: Add quirk for WORLDE easykey.25 MIDI keyboard From: Oliver Neukum To: =?UTF-8?Q?Luk=C3=A1=C5=A1_Lalinsk=C3=BD?= Cc: Greg Kroah-Hartman , linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org Date: Tue, 24 Jan 2017 09:30:51 +0100 In-Reply-To: References: <1484937994-8076-1-git-send-email-lukas@oxygene.sk> <20170121090834.GC27048@kroah.com> <1485243123.7465.26.camel@suse.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.20.5 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am Dienstag, den 24.01.2017, 08:37 +0100 schrieb Lukáš Lalinský: > On Tue, Jan 24, 2017 at 8:32 AM, Oliver Neukum > wrote: > > > > Am Montag, den 23.01.2017, 19:36 +0100 schrieb Lukáš Lalinský: > > > > > > I have uploaded both captures here - > > > https://gist.github.com/lalinsky/83148a827d5cd43e79e377d8e1b5ed0d > > > > Indeed it is does not set a configuration. Either the capture > > is incomplete or device and host violate the standard. A device > > may be left unconfigured. > > Is this may or may not? I'm not familiar with USB, so I assumed if You can leave a device unconfigured. In that case it stays in the addressed state, where its power draw is strictly limited. That is exactly what the kernel does when it is confronted with a device that would overdraw the power budget. > there is only one configuration and there is always one active, it > does not need to be set explicitly because the correct one is already > active. No, it is not. Or rather it should not be. Can you please recheck that you are capturing the whole exchange? > > We need to read the descriptors even if we > > see only one configuration to get the power budgeting right. > > Aren't those in the CONFIGURATION descriptors? Reading the STRING True. > descriptor is probably only useful if you need to print the > configuration details somewhere. Also true. > > > > Does the device work without any .ini file? > > Yes. It's a standard MIDI device, no configuration is required. So Windows by default does not read string descriptors. That is worth a thought, but we need to check. Yet I am not sure how useful that is. The first lsusb would crash the device. We'd need a quirk anyway. Regards Oliver