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[2607:7c80:54:e::133]) by mx.google.com with ESMTPS id m6si2133259pjl.60.2019.05.29.23.26.58 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 29 May 2019 23:26:58 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of batv+882e7947623448fb4484+5758+infradead.org+hch@bombadil.srs.infradead.org designates 2607:7c80:54:e::133 as permitted sender) client-ip=2607:7c80:54:e::133; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=bombadil.20170209 header.b=hC2RgOug; spf=pass (google.com: best guess record for domain of batv+882e7947623448fb4484+5758+infradead.org+hch@bombadil.srs.infradead.org designates 2607:7c80:54:e::133 as permitted sender) smtp.mailfrom=BATV+882e7947623448fb4484+5758+infradead.org+hch@bombadil.srs.infradead.org 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=nIiCMY3JsQadXOBewqvsYP0/w5h7JL3rPxkhn+Tzu2Q=; b=hC2RgOug0p2SCJXT6WId54KYZ v+nobRuR3mH8lkQdzbw3GRGrGXL36RcXf+S1IvOq3wwzeEcXxmTx0/5VfoaIk5wrOE9C0ueIe4pBB FUHhDeeqJ0gc26hf9TnS8BTkU0bkb1Al35adx+XB2zakVTJRbVXBNBjXezVRhvyl8Ua+k5Q6sw+Zd krQ0bkX4dB2nu+L2GxdJUMDNOIpY9gibsE2B7/kY12MlJd85SaR3S5PeWpZGI1lVbqLLg8V9w2xN6 zdIxrfTikliPWXb1R8Ok2wTLVU0UACNGmhYIMMEtvFHagDEhBJJoYcpDvHZsulSmwMQWdQU5b8PCM n0tHsmioA==; Received: from hch by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1hWEWS-0006ir-UP; Thu, 30 May 2019 06:26:44 +0000 Date: Wed, 29 May 2019 23:26:44 -0700 From: Christoph Hellwig To: Lucas Stach Cc: Andrew Morton , Yue Hu , =?utf-8?Q?Micha=C5=82?= Nazarewicz , Marek Szyprowski , Dmitry Vyukov , etnaviv@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-mm@kvack.org, kernel@pengutronix.de, patchwork-lst@pengutronix.de Subject: Re: [PATCH 1/2] mm: cma: export functions to get CMA base and size Message-ID: <20190530062644.GA20133@infradead.org> References: <20190529104312.27835-1-l.stach@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190529104312.27835-1-l.stach@pengutronix.de> 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, May 29, 2019 at 12:43:11PM +0200, Lucas Stach wrote: > Make them usable in modules. Some drivers want to know where their > device CMA area is located to make better decisions about the DMA > programming. NAK. This is very much a layering violation. At very least you'd need to wire this up through the DMA API and deal with dma_addr_t addresses instead of physical addresses, which are opaque to DMA using drivers. But even for that we'd need a really good rationale.