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=-7.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 0CFB2C433E2 for ; Mon, 31 Aug 2020 11:30:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CC6CA207DA for ; Mon, 31 Aug 2020 11:30:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="irsBQYiw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726821AbgHaLac (ORCPT ); Mon, 31 Aug 2020 07:30:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45910 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727037AbgHaL3l (ORCPT ); Mon, 31 Aug 2020 07:29:41 -0400 Received: from mail-vk1-xa43.google.com (mail-vk1-xa43.google.com [IPv6:2607:f8b0:4864:20::a43]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F0E95C06123F for ; Mon, 31 Aug 2020 04:29:31 -0700 (PDT) Received: by mail-vk1-xa43.google.com with SMTP id s127so1222389vkg.3 for ; Mon, 31 Aug 2020 04:29:31 -0700 (PDT) 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=JIN710TFLeLsKqRRlGqyF1G56AtXFbXojtnB+ek7vjU=; b=irsBQYiwNj1Qd8vMPMDZ4IELqeCiPeWMfkpBS3c2ZNz7mZFu5GH+I3B7C0OPEjwMVD 9jI1XXFeXGnU2b2vums9U5nwrWH6D0JR8+2oZUphySN+PnNxeueJzDWGnvYwt/oltfMD 22ZbWt8+LSAgrcF3KfEDBpLH3L3bqcmci89/GwhyaMurg6aJNkKIcnBmBAkNJinIQkY1 sd8lVRWhg89SyMdMugmmdByKiTxoWw4s11IaTQo1XbNMhUAko8qoNtgXLFhxi6gu+Sow h1kW2Fb4raKYv6Gc7y/Bhtd4ewL/1azXQH6Gakmz1md2e2rsSKov/8PxpyaUZ9MImqDH NVGg== 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=JIN710TFLeLsKqRRlGqyF1G56AtXFbXojtnB+ek7vjU=; b=XQNlg06RcnWQPZEngXTnHOxTDmi7qDYBTrWnRPBZz1QRgFqGqKSwz3hvwz+W1Ql8JS 4AEac6QkQqAWYU7lLki0qq0cgwENEjVCWx/xHwe4dewuvRTnr1LVDtJfawk715kdaNRp k9z3YiAligvG97JylwVX/gt4NGy/YUzbPLQWT5wyuRpPjfnve5gUzEfumEgidgOpCzUa dNaLiwHgZvFqOJuYK6024kNKQDkDpi3NOLch3GZrODrCEdA+vVySwYz2Od7PhtUMlcuk jA0uy3rwgyIYq7TFSJkRMz7XZZtQKo2dvkS1JE6jSK8RFl4aOndqeIdqiDLOgjPfmQgp offA== X-Gm-Message-State: AOAM532MioeCh7ocCSLNbtYvDXpjdhUCLr1+VlzWjawNzjEkkmcm7Sq6 zBpugKpBXA8e9NzusFC7qfHoKPtFnPE/ZQJ72PYQgQ== X-Google-Smtp-Source: ABdhPJw4BM3EMv3eBn1ExCUI2PJJGFIfafdTX935b2p/ZrPMqqlhkRsSr+VDzuwhyidZqSRYvMBnWkwMt12C+fZFJyw= X-Received: by 2002:a1f:2a48:: with SMTP id q69mr458218vkq.69.1598873366828; Mon, 31 Aug 2020 04:29:26 -0700 (PDT) MIME-Version: 1.0 References: <20200714121856.955680-1-hch@lst.de> <20200714121856.955680-10-hch@lst.de> <20200828020045.GT3265@brightrain.aerifal.cx> <20200828021152.GU3265@brightrain.aerifal.cx> <20200828042422.GA29734@lst.de> <20200828150942.GV3265@brightrain.aerifal.cx> <20200829083121.GA7851@lst.de> In-Reply-To: <20200829083121.GA7851@lst.de> From: Ulf Hansson Date: Mon, 31 Aug 2020 13:28:50 +0200 Message-ID: Subject: Re: [PATCH 09/10] sh: don't allow non-coherent DMA for NOMMU To: Christoph Hellwig , Rich Felker Cc: Yoshinori Sato , Linux-sh list , Linux Kernel Mailing List , "linux-mmc@vger.kernel.org" , linux-spi@vger.kernel.org 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 Sat, 29 Aug 2020 at 10:31, Christoph Hellwig wrote: > > On Fri, Aug 28, 2020 at 11:09:43AM -0400, Rich Felker wrote: > > > However, by looking at the code, one get the feeling that the DMA > > > support is somewhat prepared to be made optional. I guess it has never > > > been really tested, as the Kconfig option has "depends on HAS_DMA" - > > > and it's been like that as long as I can remember. > > > > It always worked on our "byte-banged" SPI controller, with no DMA > > controller present, before Christoph's changes in this patch series, > > Before that nommu sh builds provided a DMA mapping implementation > that even worked for the streaming side (dma_map_*), but would corrupt > data if you used dma_alloc_coherent memory to communicate with the > device. I see. > > > and seems to be working now (although I have some other, hopefully > > unrelated regressions to debug) with #ifdef CONFIG_HAS_DMA around the > > if (spi->master->dev.parent->dma_mask) block in mmc_spi_probe. That's > > probably not the right fix though -- why isn't it checking > > host->dma_dev instead and only attempting DMA setup if dma_dev is > > non-null? > > I don't think dma_dev can be NULL right now. dma_dev is assigned here: > > if (spi->master->dev.parent->dma_mask) { > struct device *dev = spi->master->dev.parent; > > host->dma_dev = dev; > > but for any OF or real bus device dma_mask never is zero (it actually is > a pointer), and the value of it also is initialized to 32-bit by default, > making this effectively an "if (1) {". The driver needs some way to > communicate if a given device actually is DMA capable or not. Or is that > purely a factor of the platform which would be a little strange. Okay, thanks for clarifying things. > > In which case we should do something like: > > > diff --git a/drivers/mmc/host/mmc_spi.c b/drivers/mmc/host/mmc_spi.c > index 39bb1e30c2d722..3b0cc9a70e6432 100644 > --- a/drivers/mmc/host/mmc_spi.c > +++ b/drivers/mmc/host/mmc_spi.c > @@ -1374,7 +1374,7 @@ static int mmc_spi_probe(struct spi_device *spi) > if (!host->data) > goto fail_nobuf1; > > - if (spi->master->dev.parent->dma_mask) { > + if (IS_ENABLED(CONFIG_HAS_DMA)) { I guess "#ifdef CONFIG_HAS_DMA", would work as well as CONFIG_HAS_DMA can't be "m". I would also suggest moving the DMA setup things into a separate function. Then when CONFIG_HAS_DMA is unset, we can use a stub. > struct device *dev = spi->master->dev.parent; > > host->dma_dev = dev; Let me cook a patch that we can try. Kind regards Uffe