From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from venus.billgatliff.com (venus.billgatliff.com [209.251.101.201]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id AACB2DDFB7 for ; Fri, 7 Nov 2008 08:42:17 +1100 (EST) Message-ID: <491364B9.607@billgatliff.com> Date: Thu, 06 Nov 2008 15:42:17 -0600 From: Bill Gatliff MIME-Version: 1.0 To: Bruce_Leonard@selinc.com Subject: Re: Using DMA References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Cc: Scott Wood , linuxppc-embedded@ozlabs.org List-Id: Linux on Embedded PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Bruce_Leonard@selinc.com wrote: > Bill Gatliff wrote on 11/06/2008 10:36:58 AM: > >> Scott Wood wrote: >>> Bruce_Leonard@selinc.com wrote: >>>> In the Cafe driver, Linux Device Drivers 3rd Edition, and >>>> DMA-mapping.txt everyone talks about how to allocate buffers using >>>> dma/pci_alloc_coherent(), but no one talks about how to actually use >>>> it. I'm pretty sure (even in my ignorance) that just allocating a DMA >>>> coherent buffer and then copying in and out of it does NOT actually >>>> engage the underlying hardware and perform a DMA transfer. >> Does the "adma" stuff address this any? >> > > What is "adma"? > > Bruce > _______________________________________________ > Linuxppc-embedded mailing list > Linuxppc-embedded@ozlabs.org > https://ozlabs.org/mailman/listinfo/linuxppc-embedded > Asynchronous DMA. See this paper, for example: http://www.power.org/devcon/07/Session_Downloads/PADC07_Aytac_Haluk_09_13_07_layout_FINAL.pdf It looks like the structure of interest is async_tx_submit. Beyond that, I can't offer much because I haven't used it. b.g. -- Bill Gatliff bgat@billgatliff.com