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=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED autolearn=ham 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 7DC3DC46464 for ; Wed, 7 Nov 2018 03:01:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 436542085B for ; Wed, 7 Nov 2018 03:01:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linaro.org header.i=@linaro.org header.b="GNQOkJnX" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 436542085B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linaro.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389382AbeKGM3e (ORCPT ); Wed, 7 Nov 2018 07:29:34 -0500 Received: from mail-ed1-f66.google.com ([209.85.208.66]:45281 "EHLO mail-ed1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389320AbeKGM3e (ORCPT ); Wed, 7 Nov 2018 07:29:34 -0500 Received: by mail-ed1-f66.google.com with SMTP id w39-v6so7844177edw.12 for ; Tue, 06 Nov 2018 19:01:09 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=j6Wudk1T2V/jEzrgGaZ7Bl/Cz6VjYO8rNqjfNWQ1HzY=; b=GNQOkJnXGtzIi6IFoSV/k+5gRciq/Sp/nRI2iBj7Lt6LzWTZGJBbdFsZ7uVuZq4vpq POE8gzXohaV5MrfkyDM7lt7mnUlyji/LaVVgbPQ3MTifAh0fLkO5xdu5pEBDqgS59Kpk E9wRKsLwNFwZanOJsEOWCBuuZfrZEsJtbWN24= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=j6Wudk1T2V/jEzrgGaZ7Bl/Cz6VjYO8rNqjfNWQ1HzY=; b=HR2yROAcgYIfsxZrqozLALkRx59W4BNyMpjTXjUyKKrXFaGC3aLNzE/UBBV4LcXPKr juGildfu+bmCN213uumwVCF49Em33jSFqEP0u/rWfFzqqBaJJYF7k131YcyFqydC/qoz 2IGS316TjjRBzmkY5CuX2J3rcu3B2HNVOjNZgvVxzSyAimP5aVp/x+QGz4SKPukqmYpF Kj+pfvrMlwdk17x+x+5AFOHO4kPQtxd6BcKznkzLfPNKpq6jwjEEvlwjRPx0rZHMOu51 lEK1ZcsBfOJ9ZjIQWNuONDfGFpQiiV2V23XFgVZWO8UtywXkN85xZK8vFa0ReWMYlYWO nWRA== X-Gm-Message-State: AGRZ1gJYPJ5Ja9/ytb3GUc1jIYCSfbhaGqJzFFddwfOMhHM2VBF/lDHu EI5iPFBnO8bdrhr1KkJRKov/74RktrsID6Q1i+CiaQ== X-Google-Smtp-Source: AJdET5eLtQELRfVcpDoSET82CbT6qe8Je1XuaUGMkINCCEd2iKuVmQsWgvBBvaRFt6DeLJIHWfzjGuoeuil+busp8Rc= X-Received: by 2002:a17:906:a301:: with SMTP id j1-v6mr354212ejz.188.1541559668864; Tue, 06 Nov 2018 19:01:08 -0800 (PST) MIME-Version: 1.0 References: <1541387810-24867-1-git-send-email-zhang.chunyan@linaro.org> <1541387810-24867-3-git-send-email-zhang.chunyan@linaro.org> In-Reply-To: From: Chunyan Zhang Date: Wed, 7 Nov 2018 11:00:57 +0800 Message-ID: Subject: Re: [PATCH RFC 2/3] mmc: sdhci-omap: Add using external dma To: Arnd Bergmann Cc: Kishon Vijay Abraham I , Ulf Hansson , Adrian Hunter , linux-mmc@vger.kernel.org, Linux Kernel Mailing List , Mark Brown , Sekhar Nori , Lyra Zhang Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 6 Nov 2018 at 20:51, Arnd Bergmann wrote: > > On 11/5/18, Kishon Vijay Abraham I wrote: > > On 05/11/18 8:46 AM, Chunyan Zhang wrote: > >> > >> + sdhci_switch_extdma(host, true); > > > > A number of devices using sdhci-omap supports ADMA. So switching to > > external > > DMA shouldn't be unconditional. > > > > IMHO sdhci.c should see if the device supports ADMA or SDMA. If not it > > should > > try switching to external DMA and if external DMA too is not supported, it > > should use PIO. > > What's the reasoning for preferring ADMA/SDMA over external DMA if > both are supported? > > I'd expect that if the external DMA for some reason is worse than > ADMA, we just wouldn't list it in the DT at all, but if it's listed and > ADMA also works, then the driver should try to use it before falling > back to ADMA. Thanks Arnd and Kishon, let's see what Andrian and Ulf would suggest, and then I will address in next version of patchset. Thanks again, Chunyan > > Arnd