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=-5.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 8145CC48BE5 for ; Thu, 17 Jun 2021 09:41:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 69415611BE for ; Thu, 17 Jun 2021 09:41:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231739AbhFQJnW (ORCPT ); Thu, 17 Jun 2021 05:43:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55578 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231730AbhFQJnV (ORCPT ); Thu, 17 Jun 2021 05:43:21 -0400 Received: from mail-ej1-x636.google.com (mail-ej1-x636.google.com [IPv6:2a00:1450:4864:20::636]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 39003C06175F for ; Thu, 17 Jun 2021 02:41:13 -0700 (PDT) Received: by mail-ej1-x636.google.com with SMTP id ho18so8765493ejc.8 for ; Thu, 17 Jun 2021 02:41:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=BMBrp+aRn4ogTXOq7rSsoT2WCWZvMYD1C/0K2uFUP9Q=; b=cu+yN/gr48xagwRF3LIo0gsjK3+kxP56KYc4muNqbfusiNDcUeu3zygS65SkmmVLxt dK+Tr7frlm4pKAG6DrJ0zb1TRfcg3+7apSa8zPFmkxzNhRWQhg2qQ9UzO1JBxBLLPj1l ozKwJC5Wu55f3MK+46q+CjzgjLzGEkX/8Z2BY= 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=BMBrp+aRn4ogTXOq7rSsoT2WCWZvMYD1C/0K2uFUP9Q=; b=kSIRRLCy7/bzWs5fgMOwEKisuFkHMDR8zYT6gkVPWOo7EdY7fZp2kb52EcGF5pN703 Gc/SK7K47n8Bk4klCgCVKlqZgGN7vdjiy+QMT1Ce6NbvxQSGDTnUlzz1+eleWw+4PTrr dx5qgHejM8aA9AX0JptgjcgPEBY83bKherSzLN5nBMOQQMJ7sTCr59ov5304tOSJ+y+s XQ1l4QELPrCNPLQQzRD1YhDubJSvMUc35q6HxFFKmGP7zR4rUpHXn8R+F0iGIHFytOcx J+Mlj04WJSgXr9abq9LOXAMSacZbitje+zhss6ABOUjXDbJcZJ04TnDkoVb/LwzKPy1f 6ADw== X-Gm-Message-State: AOAM530IIMk5sTkyfqWf/3+qHG3rE7Osq3Gjlwx54tN6ve2if2PqGnSO dTxlzPpNHjpXRJhHuekzG49dVVwU/rxe0w== X-Google-Smtp-Source: ABdhPJxxuQTWbiAkM2Kml3bMPVY2ULBaEGsPT66Uk8+kVSjadBGLcNczUm0N+cR7bIpZLIgYP/7yYA== X-Received: by 2002:a17:906:3a0e:: with SMTP id z14mr4238196eje.289.1623922871283; Thu, 17 Jun 2021 02:41:11 -0700 (PDT) Received: from mail-wr1-f54.google.com (mail-wr1-f54.google.com. [209.85.221.54]) by smtp.gmail.com with ESMTPSA id m22sm1416355ejn.50.2021.06.17.02.41.10 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 17 Jun 2021 02:41:10 -0700 (PDT) Received: by mail-wr1-f54.google.com with SMTP id a11so5971463wrt.13 for ; Thu, 17 Jun 2021 02:41:10 -0700 (PDT) X-Received: by 2002:adf:e804:: with SMTP id o4mr3456617wrm.103.1623922869865; Thu, 17 Jun 2021 02:41:09 -0700 (PDT) MIME-Version: 1.0 References: <20210427131344.139443-1-senozhatsky@chromium.org> <20210427131344.139443-9-senozhatsky@chromium.org> <10a0903a-e295-5cba-683a-1eb89a0804ed@xs4all.nl> <20210617080107.GA1422@lst.de> <20210617085233.GA4702@lst.de> In-Reply-To: <20210617085233.GA4702@lst.de> From: Tomasz Figa Date: Thu, 17 Jun 2021 18:40:58 +0900 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCHv2 8/8] videobuf2: handle non-contiguous DMA allocations To: Christoph Hellwig Cc: Sergey Senozhatsky , Hans Verkuil , Ricardo Ribalda , Mauro Carvalho Chehab , Linux Media Mailing List , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 17, 2021 at 5:52 PM Christoph Hellwig wrote: > > On Thu, Jun 17, 2021 at 05:30:11PM +0900, Tomasz Figa wrote: > > We still have use cases for dma_alloc_coherent() and DMA_ATTR_NO_KERNEL_MAPPING. > > dma_alloc_coherent does not take a flags argument, so you can't use > DMA_ATTR_NO_KERNEL_MAPPING with it. What would your use case be here > anyway? In general DMA_ATTR_NO_KERNEL_MAPPING is rather misnamed, as > usually there is a kernel mapping, just not one that is coherent and > should be used. Sorry, I meant dma_alloc_attrs() and yes, it's indeed a misnomer. Our use case basically has no need for the additional coherent mapping, so creation of it can be skipped to save some vmalloc space. (Yes, it probably only matters for 32-bit architectures.)