From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Ujfalusi Subject: Re: [PATCH v7 0/5] OMAP: McBSP: Use register cache Date: Wed, 16 Dec 2009 10:02:53 +0200 Message-ID: <200912161002.53534.peter.ujfalusi@nokia.com> References: <200912092124.14430.jkrzyszt@tis.icnet.pl> Mime-Version: 1.0 Content-Type: Text/Plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from smtp.nokia.com ([192.100.122.233]:42872 "EHLO mgw-mx06.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759129AbZLPIE4 convert rfc822-to-8bit (ORCPT ); Wed, 16 Dec 2009 03:04:56 -0500 In-Reply-To: <200912092124.14430.jkrzyszt@tis.icnet.pl> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: ext Janusz Krzysztofik Cc: Tony Lindgren , Jarkko Nikula , "linux-omap@vger.kernel.org" Hello Janusz, I'll try to go through the series. On Wednesday 09 December 2009 22:24:13 ext Janusz Krzysztofik wrote: > This could help for developing the McBSP context save/restore feature= s, as > well as solve the problem of possible register corruption, experience= d on > OMAP1510 based Amstrad Delta board at least. =46or the context save/restore feature: On OMAP3 this is not that straight forward IMHO. OMAP3 has FIFO on the McBSP ports (1024+256, or 128 word long). This buffer will be invalidated in case of OFF mode (or when context=20 save/restore is needed). So if we ever face with this situation, we need to make sure that the M= cBSP FIFO=20 is empty prior to context save, so when we are restoring we are not goi= ng to=20 loose any data. Note also, that the McBSP FIFO can not be bypassed on OMAP3, which mean= s that=20 the FIFO is most of the time is kind of full. Well, full in element mode, and mostly full in threshold mode. In other words: on OMAP3 the context save/restore is not that simple as= it is on=20 OMAP1/2. We need to make sure that the FIFO is empty at the right momen= t, which=20 can not be done with the current code, and to be honest, I can not see = how it=20 can be done, unless we branch out the OMAP3 related McBSP/DMA code, and= leave=20 the current implementation to support only OMAP1/2 class devices. --=20 P=E9ter -- To unsubscribe from this list: send the line "unsubscribe linux-omap" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html