From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4EDABC4727C for ; Thu, 1 Oct 2020 05:16:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1533A2184D for ; Thu, 1 Oct 2020 05:16:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=jonmasters-org.20150623.gappssmtp.com header.i=@jonmasters-org.20150623.gappssmtp.com header.b="AVGBn0+Y" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725883AbgJAFQk (ORCPT ); Thu, 1 Oct 2020 01:16:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57386 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725878AbgJAFQk (ORCPT ); Thu, 1 Oct 2020 01:16:40 -0400 Received: from mail-qt1-x841.google.com (mail-qt1-x841.google.com [IPv6:2607:f8b0:4864:20::841]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1D27EC061755 for ; Wed, 30 Sep 2020 22:16:40 -0700 (PDT) Received: by mail-qt1-x841.google.com with SMTP id k25so3392255qtu.4 for ; Wed, 30 Sep 2020 22:16:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=jonmasters-org.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:organization:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=aMyvN3gVuzQBj94keSmCrKk4OuJZbSTTfVDU0BztZ4o=; b=AVGBn0+Y6owZXBJwfgazLUzFbjbqhVCnIW+1imTfPSnAc4qi7Pe58QXALxxfEHH7NW Vmy+eT2KQGF2AIMXrNIMHPa8N03xNcPDw1BysPzyTAUnBrmDwNyfA8Z7LXmyUYQd1/o8 RydFp/NoH40fXqP4HLKbi4+nTGK9g3eJjstINt2w+IXfYYh/n6Gm9O/c2LARTFTxC59L GmDP40ZpueoCjSn8apq2cXt07EwlpZAZGW7F+u1qOCjoBxwIEqelJpxSQL9IZ5Yl2Uzc PyR3L4tECMB7sGhVLpgOoE5R8eq3RouzGk215efLgIqDOVkjiJNv2shFlT1s4Vagg/xo 8xMg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:organization :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=aMyvN3gVuzQBj94keSmCrKk4OuJZbSTTfVDU0BztZ4o=; b=Bi2/ZUu/X+IT779j7Q7ZW41yKsWHgb++Uth1ExMLKlpo6bo8TrVC/OPQTW2r3aSUuX zTLwRJabuVBWjIHS9+ZFVLZDemdKOkm8pYvoNyG+1V9NnR7Ei6LCVmd9xK8aTxiOHfKK S+OUl+LsJtP/tgHZJHADuil0Mv/8Z2Zqb6PBSbZrwyLwnxywEfP95vQc78jPc6c4Z7CA 15tJjeCkxz21zMtkZNbeLWb4WTHZ6n7WlaXscXATilr4ePDFCeqWQM8io2v4gvu8Ob6X ewmrfyUDSFGzCcjuAXE8RptpucOQd1yYvJiXmBBzUtpVBvYzLc5+rLAypu7Nz++ep3oa cdAg== X-Gm-Message-State: AOAM531odLvjkr9HZj5nuorugVU90tvVA5lrM0xBC0lnA1sTplJeSvWK C0nI17BrDT8HEJCVkU+P5iZJhg== X-Google-Smtp-Source: ABdhPJycizkFTjy7tefZlHhV/5gxSPPlo5/jlzPCRbOXkxTOJNHO7ZWBwNjJw8GrRDEREZvf+fBRfw== X-Received: by 2002:ac8:4442:: with SMTP id m2mr5933638qtn.73.1601529399269; Wed, 30 Sep 2020 22:16:39 -0700 (PDT) Received: from independence.bos.jonmasters.org (Boston.jonmasters.org. [50.195.43.97]) by smtp.gmail.com with ESMTPSA id 16sm4944270qks.102.2020.09.30.22.16.38 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 30 Sep 2020 22:16:38 -0700 (PDT) Subject: Re: dma-coherent property for PCIe Root To: Valmiki , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Cc: lorenzo.pieralisi@arm.com, bhelgaas@google.com, robh@kernel.org References: <1512d7b5-54c6-3b87-0090-5e370955223e@gmail.com> From: Jon Masters Organization: World Organi{s,z}ation of Broken Dreams Message-ID: <269995f2-d57b-d218-8730-fe729cc9dec2@jonmasters.org> Date: Thu, 1 Oct 2020 01:16:10 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <1512d7b5-54c6-3b87-0090-5e370955223e@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On 9/14/20 1:23 AM, Valmiki wrote: > Hi All, > > How does "dma-coherent" property will work for PCIe as RC on an > ARM SOC ? > Because the end point device drivers are the one which will request dma > buffers and Root port driver doesn't involve in data path of end point > except for handling interrupts. > > How does EP DMA buffers will be hardware coherent if RC driver exposes > dma-coherent property ? This simply means that the RC supports maintaining coherency, it doesn't mean that the RC driver does anything. It's a property of the hardware. Jon. -- Computer Architect