From mboxrd@z Thu Jan 1 00:00:00 1970 From: viresh.kumar@st.com (Viresh Kumar) Date: Tue, 23 Aug 2011 09:52:49 +0530 Subject: [PATCH 16/18] dmaengine/amba-pl08x: Add support for sg len greater than one for slave transfers In-Reply-To: <20110821083306.GA12028@n2100.arm.linux.org.uk> References: <5d691ab0c4f447c9f324213d8d740ac61d1739a1.1311936524.git.viresh.kumar@st.com> <20110814083618.GE4986@n2100.arm.linux.org.uk> <4E4CCF7B.8060704@st.com> <20110821083306.GA12028@n2100.arm.linux.org.uk> Message-ID: <4E532B19.6000103@st.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 8/21/2011 2:03 PM, Russell King - ARM Linux wrote: >> > I am not sure if i get this completely. In memcpy, we still don't support >> > more than one sg. We have created a new member in txd, which keeps track of >> > data (addresses, len). > Yes, but we shouldn't need to translate it into any kind of scatterlist. > Ok. I way out is keeping two separate variables in txd, list for slave transfers, and pointer to single element for memcpy. And that looks to be even bad to me. Why waste memory, for second variable. Or create union of both. One more thing, we can actually have scatter gather in memcpy too in future. This will be helpful then also. But surely that's something not implemented currently. -- viresh From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751689Ab1HWEXn (ORCPT ); Tue, 23 Aug 2011 00:23:43 -0400 Received: from eu1sys200aog107.obsmtp.com ([207.126.144.123]:55733 "EHLO eu1sys200aog107.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750698Ab1HWEXh (ORCPT ); Tue, 23 Aug 2011 00:23:37 -0400 Message-ID: <4E532B19.6000103@st.com> Date: Tue, 23 Aug 2011 09:52:49 +0530 From: Viresh Kumar User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:6.0) Gecko/20110812 Thunderbird/6.0 MIME-Version: 1.0 To: Russell King - ARM Linux Cc: "linus.walleij@linaro.org" , Pratyush ANAND , Rajeev KUMAR , Bhupesh SHARMA , Shiraz HASHIM , "vinod.koul@intel.com" , "linux-kernel@vger.kernel.org" , Vipin KUMAR , Armando VISCONTI , Amit VIRDI , Vipul Kumar SAMAR , "viresh.linux@gmail.com" , Deepak SIKRI , "dan.j.williams@intel.com" , "linux-arm-kernel@lists.infradead.org" Subject: Re: [PATCH 16/18] dmaengine/amba-pl08x: Add support for sg len greater than one for slave transfers References: <5d691ab0c4f447c9f324213d8d740ac61d1739a1.1311936524.git.viresh.kumar@st.com> <20110814083618.GE4986@n2100.arm.linux.org.uk> <4E4CCF7B.8060704@st.com> <20110821083306.GA12028@n2100.arm.linux.org.uk> In-Reply-To: <20110821083306.GA12028@n2100.arm.linux.org.uk> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/21/2011 2:03 PM, Russell King - ARM Linux wrote: >> > I am not sure if i get this completely. In memcpy, we still don't support >> > more than one sg. We have created a new member in txd, which keeps track of >> > data (addresses, len). > Yes, but we shouldn't need to translate it into any kind of scatterlist. > Ok. I way out is keeping two separate variables in txd, list for slave transfers, and pointer to single element for memcpy. And that looks to be even bad to me. Why waste memory, for second variable. Or create union of both. One more thing, we can actually have scatter gather in memcpy too in future. This will be helpful then also. But surely that's something not implemented currently. -- viresh