From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755462Ab3BDVsZ (ORCPT ); Mon, 4 Feb 2013 16:48:25 -0500 Received: from moutng.kundenserver.de ([212.227.126.187]:63248 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754780Ab3BDVsW (ORCPT ); Mon, 4 Feb 2013 16:48:22 -0500 From: Arnd Bergmann To: Linus Walleij Subject: Re: [PATCH v7 01/10] ARM: davinci: move private EDMA API to arm/common Date: Mon, 4 Feb 2013 21:47:38 +0000 User-Agent: KMail/1.12.2 (Linux/3.8.0-4-generic; KDE/4.3.2; x86_64; ; ) Cc: Cyril Chemparathy , Mark Brown , balbi@ti.com, Sergei Shtylyov , Linux Documentation List , Lindgren , "Russell King - ARM Linux" , Vinod Koul , "Nair, Sandeep" , Chris Ball , Matt Porter , Devicetree Discuss , Rob Herring , Linux OMAP List , ARM Kernel List , Linux DaVinci Kernel List , "Cousson, Benoit" , Linux MMC List , Linux Kernel Mailing List , Landley , Dan Williams , Linux SPI Devel List References: <510C2A47.1090607@mvista.com> <20130204203358.GX4720@opensource.wolfsonmicro.com> In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201302042147.38407.arnd@arndb.de> X-Provags-ID: V02:K0:Or3zkanQJNu3v103eKzZpnRe+oD/YIFCeIZ7lsUkSV8 FVFxsKlefYnwvCm5+TJxXQfsUYXBOe4rRYTXJ86AiEfPWgunS9 Ofyrj6dGLQc/itjyJnxx9j7REeeIfZfyd/65U93qhZD/SnfdRH Ovfeo9eqj/JHV3rtQX3MoTaEspEpbgQZ5cwePtZASsCksvRWwP P2YUMOSRnO8gpAkvvnyGXKf6M90Icqi7LR93InJrNbtTddSWil wT8o0M+C26izG5RPNkpPhUDP4CUap38pcdTwEkc6TnrAIdutaL JzJ432FNw4T5CfllAwY3ROueZiNUPQgQ7MCLSyW2hdz/3DRMN5 1q0ve9lS/e1U4vyMob9Y= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Monday 04 February 2013, Linus Walleij wrote: > So I think the above concerns are moot. The callback we can > set on cookies is entirely optional, and it's even implemented by > each DMA engine, and some may not even support it but require > polling, and then it won't even be implemented by the driver. Just to ensure that everybody is talking about the same thing here: Is it just the callback that is optional, or also the interrupt coming from the hardware? With NAPI, you want to avoid both, since getting an interrupt for every packet adds noticeable overhead, but you still want to be able to tell the hardware that you are fed up with polling and would like to get an interrupt again when the next data arrives (ideally, after either a little time has passed after the next packet, or a specific number of packets has arrived). Arnd From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH v7 01/10] ARM: davinci: move private EDMA API to arm/common Date: Mon, 4 Feb 2013 21:47:38 +0000 Message-ID: <201302042147.38407.arnd@arndb.de> References: <510C2A47.1090607@mvista.com> <20130204203358.GX4720@opensource.wolfsonmicro.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: spi-devel-general-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: Linus Walleij Cc: Sergei Shtylyov , Linux Documentation List , Lindgren , Russell King - ARM Linux , Vinod Koul , "Nair, Sandeep" , Cyril Chemparathy , Chris Ball , Matt Porter , Devicetree Discuss , Rob Herring , Linux OMAP List , ARM Kernel List , Linux DaVinci Kernel List , "Cousson, Benoit" , Mark Brown , Linux MMC List , Linux Kernel Mailing List , balbi-l0cyMroinI0@public.gmane.org, Landley , Dan Williams Linux List-Id: devicetree@vger.kernel.org On Monday 04 February 2013, Linus Walleij wrote: > So I think the above concerns are moot. The callback we can > set on cookies is entirely optional, and it's even implemented by > each DMA engine, and some may not even support it but require > polling, and then it won't even be implemented by the driver. Just to ensure that everybody is talking about the same thing here: Is it just the callback that is optional, or also the interrupt coming from the hardware? With NAPI, you want to avoid both, since getting an interrupt for every packet adds noticeable overhead, but you still want to be able to tell the hardware that you are fed up with polling and would like to get an interrupt again when the next data arrives (ideally, after either a little time has passed after the next packet, or a specific number of packets has arrived). Arnd ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_jan From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH v7 01/10] ARM: davinci: move private EDMA API to arm/common Date: Mon, 4 Feb 2013 21:47:38 +0000 Message-ID: <201302042147.38407.arnd@arndb.de> References: <510C2A47.1090607@mvista.com> <20130204203358.GX4720@opensource.wolfsonmicro.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Sergei Shtylyov , Linux Documentation List , Lindgren , Russell King - ARM Linux , Vinod Koul , "Nair, Sandeep" , Cyril Chemparathy , Chris Ball , Matt Porter , Devicetree Discuss , Rob Herring , Linux OMAP List , ARM Kernel List , Linux DaVinci Kernel List , "Cousson, Benoit" , Mark Brown , Linux MMC List , Linux Kernel Mailing List , balbi-l0cyMroinI0@public.gmane.org, Landley , Dan Williams , Linux To: Linus Walleij Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: spi-devel-general-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: linux-spi.vger.kernel.org On Monday 04 February 2013, Linus Walleij wrote: > So I think the above concerns are moot. The callback we can > set on cookies is entirely optional, and it's even implemented by > each DMA engine, and some may not even support it but require > polling, and then it won't even be implemented by the driver. Just to ensure that everybody is talking about the same thing here: Is it just the callback that is optional, or also the interrupt coming from the hardware? With NAPI, you want to avoid both, since getting an interrupt for every packet adds noticeable overhead, but you still want to be able to tell the hardware that you are fed up with polling and would like to get an interrupt again when the next data arrives (ideally, after either a little time has passed after the next packet, or a specific number of packets has arrived). Arnd ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_jan From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Mon, 4 Feb 2013 21:47:38 +0000 Subject: [PATCH v7 01/10] ARM: davinci: move private EDMA API to arm/common In-Reply-To: References: <510C2A47.1090607@mvista.com> <20130204203358.GX4720@opensource.wolfsonmicro.com> Message-ID: <201302042147.38407.arnd@arndb.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Monday 04 February 2013, Linus Walleij wrote: > So I think the above concerns are moot. The callback we can > set on cookies is entirely optional, and it's even implemented by > each DMA engine, and some may not even support it but require > polling, and then it won't even be implemented by the driver. Just to ensure that everybody is talking about the same thing here: Is it just the callback that is optional, or also the interrupt coming from the hardware? With NAPI, you want to avoid both, since getting an interrupt for every packet adds noticeable overhead, but you still want to be able to tell the hardware that you are fed up with polling and would like to get an interrupt again when the next data arrives (ideally, after either a little time has passed after the next packet, or a specific number of packets has arrived). Arnd