From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans-Christian Egtvedt Subject: Can DMA address, periods, buffer size, etc change after hw_params is called? Date: Thu, 29 Jan 2009 08:18:25 +0100 Message-ID: <20090129081825.241be9e4@hcegtvedt> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from relay.atmel.no (relay.atmel.no [80.232.32.139]) by alsa0.perex.cz (Postfix) with ESMTP id 9626F103851 for ; Thu, 29 Jan 2009 08:18:27 +0100 (CET) Received: from hcegtvedt (dhcp-252-160.norway.atmel.com [10.191.252.160]) by relay.atmel.no (8.13.4/8.13.4) with ESMTP id n0T7HDEk024815 for ; Thu, 29 Jan 2009 08:17:14 +0100 (CET) (envelope-from hans-christian.egtvedt@atmel.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 Hi, I wonder if I must take care handling changes in DMA address, number of periods and period size in the prepare callback? Or are these locked after the first time prepare is called? The reason I ask is because I'm developing a new ALSA driver and I prepare a cyclic DMA transfer in the first prepare callback. Additional calls to prepare will not do anything DMA stuff. The cyclic DMA transfer is then released in the close callback. Should I after the open and hw_params calls be ready to handle any change at all regarding DMA buffer address, periods and/or number of periods? I hope I made sense in this email (-: -- Best regards, Hans-Christian Egtvedt