Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753226AbYCLC3L (ORCPT ); Tue, 11 Mar 2008 22:29:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751768AbYCLC25 (ORCPT ); Tue, 11 Mar 2008 22:28:57 -0400 Received: from de01egw02.freescale.net ([192.88.165.103]:58004 "EHLO de01egw02.freescale.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751729AbYCLC24 convert rfc822-to-8bit (ORCPT ); Tue, 11 Mar 2008 22:28:56 -0400 X-MimeOLE: Produced By Microsoft Exchange V6.5 Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Subject: RE: [PATCH 2/2] Add device_prep_dma_interrupt support to fsldma.c Date: Wed, 12 Mar 2008 10:28:49 +0800 Message-ID: In-Reply-To: X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: [PATCH 2/2] Add device_prep_dma_interrupt support to fsldma.c Thread-Index: AciDwqKwKblje3mXSA6S13WXe3U1LgAJBEKQ References: <1205205917-21861-1-git-send-email-wei.zhang@freescale.com> <1205205917-21861-2-git-send-email-wei.zhang@freescale.com> From: "Zhang Wei" To: "Dan Williams" Cc: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1436 Lines: 43 Hi, Dan, > -----Original Message----- > From: dan.j.williams@gmail.com > > + > > + /* Set End-of-link to the last link descriptor of > new list*/ > > + set_ld_eol(fsl_chan, new); > > Question, is 'set_ld_eol' safe to call on descriptors that may not be > the last in the list? For example what about the following sequence: set_ld_eol() is a safe function, which is only for preparing the tx descriptors lists. When adding prepared tx descriptior list to DMA channel tx list, the function append_ld_queue() should be called. > > /* prepare two descriptors */ > tx1 = fsl_dma_prep_interrupt(chan); > tx2 = fsl_dma_prep_memcpy(chan); > > /* submit out of order */ > tx2->tx_submit(tx2); > tx1->tx_submit(tx1); > > This is only a concern if you plan to support channel switching at > some point. For example, switching from a memcpy channel to an xor > channel. > It's no problem. :) In fact, I've added out of order testing codes in fsl_dma_self_test() function. But I have a question about device_prep_dma_interrupt(), which is no way to assign dest and src address. Is it a null tx action dma_async_tx_descriptor except to trigger an interrupt? Thanks! Wei. -- 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/