Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964874AbbGHN5t (ORCPT ); Wed, 8 Jul 2015 09:57:49 -0400 Received: from mx0b-00176a03.pphosted.com ([67.231.157.48]:32092 "EHLO mx0b-00176a03.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934296AbbGHN5s (ORCPT ); Wed, 8 Jul 2015 09:57:48 -0400 Message-ID: <559D2C51.9080108@ge.com> Date: Wed, 8 Jul 2015 14:57:37 +0100 From: Martyn Welch User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Dmitry Kalinkin , Alessio Igor Bogani CC: , Greg Kroah-Hartman , Igor Alekseev , LKML , Manohar Vanga Subject: Re: [PATCHv3 08/16] staging: vme_user: provide DMA functionality References: <1432814833-5320-1-git-send-email-dmitry.kalinkin@gmail.com> <1432814833-5320-9-git-send-email-dmitry.kalinkin@gmail.com> <20150613002807.GA17459@kroah.com> <559A8117.4060701@ge.com> <559A9556.4040303@ge.com> In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [3.159.212.192] X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2015-07-08_07:,, signatures=0 X-Proofpoint-Spam-Details: rule=notspam policy=default score=1 spamscore=1 suspectscore=2 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1506180000 definitions=main-1507080220 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1177 Lines: 26 On 07/07/15 11:52, Dmitry Kalinkin wrote: > The API I had in mind would have only vme_master_read and > vme_master_write that would take absolute addresses (not relative to > any window). These variants of access functions would then try to > reuse any window that is already able to serve the request or wait > for a free window and reconfigure it for the need of the request. I'm a little concerned by the latency this might cause, especially if there is one device which is negatively affected by latency. Handling RORA interrupts would be "interesting" if all the windows were dynamically allocated at the time at which an interrupt came in. Martyn -- Martyn Welch (Lead Software Engineer) | Registered in England and Wales GE Intelligent Platforms | (3828642) at 100 Barbirolli Square T +44(0)1327322748 | Manchester, M2 3AB E martyn.welch@ge.com | VAT:GB 927559189 -- 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/