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=-10.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,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 EE010C432C2 for ; Tue, 24 Sep 2019 13:55:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C5BC52146E for ; Tue, 24 Sep 2019 13:55:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ti.com header.i=@ti.com header.b="sqMOR+nE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2409690AbfIXNz7 (ORCPT ); Tue, 24 Sep 2019 09:55:59 -0400 Received: from fllv0016.ext.ti.com ([198.47.19.142]:56312 "EHLO fllv0016.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726252AbfIXNz6 (ORCPT ); Tue, 24 Sep 2019 09:55:58 -0400 Received: from lelv0265.itg.ti.com ([10.180.67.224]) by fllv0016.ext.ti.com (8.15.2/8.15.2) with ESMTP id x8ODtsne021248; Tue, 24 Sep 2019 08:55:54 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1569333354; bh=btPV7Sjr/rnEMgxUyHIr3zvLMVUcIGMOqQpe2lo8C08=; h=Subject:From:To:CC:References:Date:In-Reply-To; b=sqMOR+nEhYtaIHN8ZfAV27zmxddiIyaiO0QpWO6GjUVM0wBZSfWsRC2fTa82Vf+Vr vS95zY2N8mqIZx38raNe+Paijr6lj3LnbIOd+dNgTf0Y7JZoRZAwDSFwjDua1SO3Ot feBPb/3xi09jUCp19BYAa1ablBcjoeb/HTXMuZnM= Received: from DLEE104.ent.ti.com (dlee104.ent.ti.com [157.170.170.34]) by lelv0265.itg.ti.com (8.15.2/8.15.2) with ESMTPS id x8ODtsP8124713 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 24 Sep 2019 08:55:54 -0500 Received: from DLEE109.ent.ti.com (157.170.170.41) by DLEE104.ent.ti.com (157.170.170.34) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1713.5; Tue, 24 Sep 2019 08:55:47 -0500 Received: from lelv0327.itg.ti.com (10.180.67.183) by DLEE109.ent.ti.com (157.170.170.41) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1713.5 via Frontend Transport; Tue, 24 Sep 2019 08:55:46 -0500 Received: from [192.168.2.6] (ileax41-snat.itg.ti.com [10.172.224.153]) by lelv0327.itg.ti.com (8.15.2/8.15.2) with ESMTP id x8ODtp6I124895; Tue, 24 Sep 2019 08:55:52 -0500 Subject: Re: [PATCH 1/3] dt-bindings: dma: Add documentation for DMA domains From: Peter Ujfalusi To: Rob Herring CC: , , , , References: <20190910115037.23539-1-peter.ujfalusi@ti.com> <20190910115037.23539-2-peter.ujfalusi@ti.com> <5d7ba96c.1c69fb81.ee467.32b9@mx.google.com> <82254a3e-12fe-14d8-d49a-6627dd1d3559@ti.com> Message-ID: Date: Tue, 24 Sep 2019 16:56:32 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <82254a3e-12fe-14d8-d49a-6627dd1d3559@ti.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 16/09/2019 14.21, Peter Ujfalusi wrote: > > > On 13/09/2019 17.36, Rob Herring wrote: >> On Tue, Sep 10, 2019 at 02:50:35PM +0300, Peter Ujfalusi wrote: >>> On systems where multiple DMA controllers available, non Slave (for example >>> memcpy operation) users can not be described in DT as there is no device >>> involved from the DMA controller's point of view, DMA binding is not usable. >>> However in these systems still a peripheral might need to be serviced by or >>> it is better to serviced by specific DMA controller. >>> When a memcpy is used to/from a memory mapped region for example a DMA in the >>> same domain can perform better. >>> For generic software modules doing mem 2 mem operations it also matter that >>> they will get a channel from a controller which is faster in DDR to DDR mode >>> rather then from the first controller happen to be loaded. >>> >>> This property is inherited, so it may be specified in a device node or in any >>> of its parent nodes. >> >> If a device needs mem2mem dma, I think we should just use the existing >> dma binding. The provider will need a way to define cell values which >> mean mem2mem. > > But isn't it going to be an abuse of the binding? Each DMA controller > would hack this in different ways, probably using out of range DMA > request/trigger number or if they have direction in the binding or some > other parameter would be set to something invalid... > >> For generic s/w, it should be able to query the dma speed or get a >> preferred one IMO. It's not a DT problem. >> >> We measure memcpy speeds at boot time to select the fastest >> implementation for a chip, why not do that for mem2mem DMA? > > It would make an impact on boot time since the tests would need to be > done with a large enough copy to be able to see clearly which one is faster. > > Also we should be able to handle different probing orders: > client1 should have mem2mem channel from dma2. > > - dma1 probes > - client1 probes and asks for a mem2mem channel > - dma2 probes > > Here client1 should deffer until dma2 is probed. > > Probably the property should be dma-mem2mem-domain to be more precise on > it's purpose and avoid confusion? Is it OK if I go with dma-mem2mem-domain or dma-mem2mem-controller for v2, but keeping the logic and approach intact? Regards, - Péter > >> >>> >>> Signed-off-by: Peter Ujfalusi >>> --- >>> .../devicetree/bindings/dma/dma-domain.yaml | 88 +++++++++++++++++++ >>> 1 file changed, 88 insertions(+) >>> create mode 100644 Documentation/devicetree/bindings/dma/dma-domain.yaml >> >> Note that you have several errors in your schema. Run 'make dt_bindings_check'. > > That does not do anything on my system, but git dt-doc-validate running > via https://github.com/robherring/yaml-bindings.git. > > - Péter > > Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. > Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki > Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki