From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarkko Nikula Subject: Re: system suspend and live audio streams Date: Mon, 16 Apr 2012 19:10:44 +0300 Message-ID: <4F8C4484.5000605@bitmer.com> References: <4F8B1EF3.9040802@bitmer.com> <4F8BF729.20906@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from bitmer.com (bitmer.com [213.157.87.50]) by alsa0.perex.cz (Postfix) with ESMTP id C5C6E104128 for ; Mon, 16 Apr 2012 18:11:48 +0200 (CEST) In-Reply-To: <4F8BF729.20906@ti.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: Peter Ujfalusi Cc: alsa-devel , Grazvydas Ignotas List-Id: alsa-devel@alsa-project.org On 04/16/2012 01:40 PM, Peter Ujfalusi wrote: > Because we need to write registers (configure McPBSP). > >> I don't know immediately does this require any major changes for McBSP >> register access that are done in function calls before omap_mcbsp_start >> (IRCC hwmod might set already ICLK gating for register access) but some >> code is needed to deal with McBSP register cache restore (due OMAP >> OFFMODE that might be hit) and most probably for McBSP FIFO draining as >> well. > I meant above if hwmod has already set ICLK so (was it autogating?) that manual enable/disable cycle for ICLK may not be needed for register access if clock is automatically gated. I have vague memory that I saw something like this in hwmod for some block but I'm not sure about this. But that reminds me that did we have some use-case where FCLK was needed during register access? > What we need to do is to have proper register store/restore for McBSP to > support suspend during audio activity. But. Even with that if the McBSP > is hitting OFF mode we will loose the McBSP FIFO content (invalidated). > This means we are going to have missing samples. Probably the user will > not going to notice it, but it is going to happen. For register store/restore there is already much implemented thanks to Janusz's register cache workaround for OMAP1510 :-) For FIFO I was thinking, if possible, to drain it out before going to suspend. -- Jarkko