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=-2.4 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, URIBL_BLOCKED,USER_AGENT_MUTT 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 36C2BC4321D for ; Mon, 20 Aug 2018 06:23:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CE2B62152D for ; Mon, 20 Aug 2018 06:23:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="gCv2HkzR" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CE2B62152D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.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 S1726229AbeHTJhv (ORCPT ); Mon, 20 Aug 2018 05:37:51 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:48082 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726026AbeHTJhu (ORCPT ); Mon, 20 Aug 2018 05:37:50 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=ty1i59lLQIOumb6ra5mWlyUebheLVKRTqb0SYJxYM1k=; b=gCv2HkzRPvOdZF2wEKvWEi7PY tsHXB5U0Zwvpr7bWFAbEBn1sGh4FGaLooZpBMaK0hzw5SYwRyVCx6hKjv2t3lm3rlm50aRpoVz19N 06VbTglJWFJ3w3k8BBjGR4hg1Oga1NCrFo6nlqIr8C22cQ7zuijrrfeOpwiv1nVb1iM765Y3ryK1Z qrdwxUIwjyuKJrf9WESCcBh9PyCf35Hf7rh4HvomMGMIApFn4Fo6ejFgwP7jh7sO/YyYDiHXNEXk0 eT+KS7mQ8fHcJE7i8YS17tgc1QfMSb16Ne3TthOmDTlWpEDxUh0S1x+E99a5bLats6hGGsW4X6zd5 cYodpDHZg==; Received: from hch by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1frdb4-0006Jq-9c; Mon, 20 Aug 2018 06:23:26 +0000 Date: Sun, 19 Aug 2018 23:23:26 -0700 From: Christoph Hellwig To: David Miller Cc: brian.brooks@linaro.org, antoine.tenart@bootlin.com, maxime.chevallier@bootlin.com, ymarkman@marvell.com, stefanc@marvell.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, bjorn.topel@intel.com, brian.brooks@arm.com Subject: Re: [PATCH] net: mvpp2: avoid bouncing buffers Message-ID: <20180820062326.GA22222@infradead.org> References: <20180820024730.9147-1-brian.brooks@linaro.org> <20180819.195505.1988137313680465320.davem@davemloft.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180819.195505.1988137313680465320.davem@davemloft.net> User-Agent: Mutt/1.9.2 (2017-12-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Aug 19, 2018 at 07:55:05PM -0700, David Miller wrote: > From: Brian Brooks > Date: Sun, 19 Aug 2018 21:47:30 -0500 > > > @@ -5126,6 +5126,12 @@ static int mvpp2_probe(struct platform_device *pdev) > > } > > > > if (priv->hw_version == MVPP22) { > > + /* Platform code may have set dev->dma_mask to point > > + * to dev->coherent_dma_mask, but we want to ensure > > + * they take different values due to comment below. > > + */ > > + pdev->dev.dma_mask = &priv->dma_mask; > > The platform code might be doing this exactly because it cannot support > different coherent and streaming DMA masks. > > Well, in any case, the platform code is doing it for a reason and > overriding this in a "driver" of all places seems totally > inappropriate and at best a layering violation. > > I would rather you fix this in a way that involves well defined APIs > that set the DMA masks or whatever to the values that you need, rather > than going behind the platform code's back and changing the DMA mask > pointer like this. Agreed. What platform do you see this issue on?