Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934620AbbGHOrJ (ORCPT ); Wed, 8 Jul 2015 10:47:09 -0400 Received: from mail-wg0-f44.google.com ([74.125.82.44]:36749 "EHLO mail-wg0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933552AbbGHOrG convert rfc822-to-8bit (ORCPT ); Wed, 8 Jul 2015 10:47:06 -0400 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2102\)) Subject: Re: [PATCHv3 08/16] staging: vme_user: provide DMA functionality From: Dmitry Kalinkin In-Reply-To: <559D2C51.9080108@ge.com> Date: Wed, 8 Jul 2015 17:47:00 +0300 Cc: Alessio Igor Bogani , devel@driverdev.osuosl.org, Greg Kroah-Hartman , Igor Alekseev , LKML , Manohar Vanga Content-Transfer-Encoding: 8BIT Message-Id: 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> <559D2C51.9080108@ge.com> To: Martyn Welch X-Mailer: Apple Mail (2.2102) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1069 Lines: 18 > On 08 Jul 2015, at 16:57, Martyn Welch wrote: > > > > 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. Latency-critical windows can be statically allocated using current resource based API.-- 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/