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=-8.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 6A298C56201 for ; Mon, 26 Oct 2020 02:21:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2C23B217A0 for ; Mon, 26 Oct 2020 02:21:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1421380AbgJZCVO (ORCPT ); Sun, 25 Oct 2020 22:21:14 -0400 Received: from szxga06-in.huawei.com ([45.249.212.32]:3004 "EHLO szxga06-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1421377AbgJZCVO (ORCPT ); Sun, 25 Oct 2020 22:21:14 -0400 Received: from DGGEMS406-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga06-in.huawei.com (SkyGuard) with ESMTP id 4CKJVN40gBzhb9K; Mon, 26 Oct 2020 10:21:16 +0800 (CST) Received: from [127.0.0.1] (10.174.178.230) by DGGEMS406-HUB.china.huawei.com (10.3.19.206) with Microsoft SMTP Server id 14.3.487.0; Mon, 26 Oct 2020 10:21:09 +0800 Subject: Re: [PATCH v2 1/2] arm64: dts: broadcom: clear the warnings caused by empty dma-ranges To: Arnd Bergmann CC: Florian Fainelli , Rob Herring , Ray Jui , Scott Branden , bcm-kernel-feedback-list , Andy Gross , Bjorn Andersson , linux-arm-msm , devicetree , linux-arm-kernel , linux-kernel References: <20201016090833.1892-1-thunder.leizhen@huawei.com> <20201016090833.1892-2-thunder.leizhen@huawei.com> <0eee3fd2-7400-7de7-27a7-7fcaa0955854@gmail.com> From: "Leizhen (ThunderTown)" Message-ID: <07ab3bdd-dcb1-5a59-d813-f82451b3f028@huawei.com> Date: Mon, 26 Oct 2020 10:21:08 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.178.230] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On 2020/10/23 15:17, Arnd Bergmann wrote: > On Sun, Oct 18, 2020 at 4:10 AM Leizhen (ThunderTown) > wrote: >> On 2020/10/17 3:27, Florian Fainelli wrote: >>> On 10/16/20 11:23 AM, Arnd Bergmann wrote: >>>> On Fri, Oct 16, 2020 at 6:48 PM Florian Fainelli wrote: >>>>> On 10/16/20 4:01 AM, Arnd Bergmann wrote: >>>>>> On Fri, Oct 16, 2020 at 11:09 AM Zhen Lei wrote: >>>>>>> >>>>>>> Suggested-by: Arnd Bergmann >>>>>>> Signed-off-by: Zhen Lei >>>>>> >>>>>> Acked-by: Arnd Bergmann >>>>>> >>>>>> I see that at least the 'bcd' and 'xhci' devices in fact try to >>>>>> use 64-bit DMA. It would be good to test this on actual >>>>>> hardware to ensure that it works correctly when this is enabled. >>>>>> >>>>>> Ideally avoiding the swiotlb bounce buffering should only >>>>>> make it faster here, but there are many chips on which >>>>>> 64-bit DMA is broken in some form. >>>>> >>>>> Is this change really an improvement though? This 'usb' pseudo bus node >>>>> could just keep being defined with #address-cells = <1> and #size-cells >>>>> = <1> so as to satisfy the 'reg' definition however we could just adjust >>>>> dma-ranges to indicate full 64-bit addressing capability. Would not that >>>>> work? >>>> >>>> When #address-cells is '1', you cannot specify dma-ranges that >>>> go beyond a 32-bit address range. >>> >>> Would not it be enough to remove the 'dma-ranges' property though? Sorry >>> for being slow here. >> >> Remove the 'dma-ranges' property should also work. After all, it is equivalent >> to the original empty dma-ranges scheme. In addition, since the IOMMU nodes are >> defined, it should be enabled. > > Are you sure? I was expecting the IOMMU not to get used here since > the devices do contain list an 'iommus' property. OK，If the SMMU maybe disabled, then your proposal is necessary. > > Arnd > > . >