From mboxrd@z Thu Jan 1 00:00:00 1970 From: Clemens Ladisch Subject: Re: [PATCH 1/2] ALSA: update sync header when streams are linked/unlinked Date: Wed, 23 May 2012 21:32:08 +0200 Message-ID: <4FBD3B38.4050005@ladisch.de> References: <1337716442-10411-1-git-send-email-pierre-louis.bossart@linux.intel.com> <4FBD331E.7010802@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from out5-smtp.messagingengine.com (out5-smtp.messagingengine.com [66.111.4.29]) by alsa0.perex.cz (Postfix) with ESMTP id 471FF24141 for ; Wed, 23 May 2012 21:32:34 +0200 (CEST) Received: from compute2.internal (compute2.nyi.mail.srv.osa [10.202.2.42]) by gateway1.nyi.mail.srv.osa (Postfix) with ESMTP id 6746F20DC7 for ; Wed, 23 May 2012 15:32:33 -0400 (EDT) Received: from [192.168.42.198] (unknown [46.115.35.238]) by mail.messagingengine.com (Postfix) with ESMTPA id B11578E0200 for ; Wed, 23 May 2012 15:32:31 -0400 (EDT) In-Reply-To: <4FBD331E.7010802@linux.intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: alsa-devel-bounces@alsa-project.org Errors-To: alsa-devel-bounces@alsa-project.org To: alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org Pierre-Louis Bossart wrote: >> The fact that the driver currently sets only the card number is >> actually problematic. It's not unique enough. This should be fixed. >> But, exposing the substream bitmask doesn't help much because it can't >> be fully implemented in the sync id size. If you need to know which >> streams are linked, loop over all streams and check the sync id. > > If I understand you well, the sync id should be a unique identifier > shared by all linked streams in the same group. Just to clarify: does the sync id identify streams that are linked, or streams that can be started atomically when linked? Because at the moment, all drivers implement the latter. Furthermore, it's possible to link completely unrelated devices, so not even the card number could be used for the former. Regards, Clemens