Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752701Ab0BWHgr (ORCPT ); Tue, 23 Feb 2010 02:36:47 -0500 Received: from out2.smtp.messagingengine.com ([66.111.4.26]:59465 "EHLO out2.smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752240Ab0BWHgq (ORCPT ); Tue, 23 Feb 2010 02:36:46 -0500 X-Sasl-enc: S6yz3tIf8osXQm/5+KjZBWF7X6dzsHXVXiZQOR3JCoYc 1266910605 Message-ID: <4B83858C.8010305@ladisch.de> Date: Tue, 23 Feb 2010 08:36:44 +0100 From: Clemens Ladisch User-Agent: Thunderbird 2.0.0.23 (Windows/20090812) MIME-Version: 1.0 To: Henrique de Moraes Holschuh CC: ibm-acpi-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: [PATCH] thinkpad-acpi: fix return value of volume callbacks References: <4B825228.8050405@ladisch.de> <20100223031220.GI30470@khazad-dum.debian.net> In-Reply-To: <20100223031220.GI30470@khazad-dum.debian.net> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1017 Lines: 23 Henrique de Moraes Holschuh wrote: > On Mon, 22 Feb 2010, Clemens Ladisch wrote: > > Fix up the volume status setting functions to return a non-zero value if > > the control value has changed, so that the ALSA framework can correctly > > generate control change notifications. > > Please explain... ALSA sends notifications to all mixer application when the value of any mixer control has changed. To be able to avoid sending them for controls that did not actually change, it uses the return value of the .put callback: 0 means the control value did not change; 1 means it has changed (or might have changed), and a notification is to be sent. Regards, Clemens -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/