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=-1.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=unavailable 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 F0137C282CE for ; Mon, 15 Apr 2019 07:14:38 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id BFDB320825 for ; Mon, 15 Apr 2019 07:14:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="fEWCzqe9" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BFDB320825 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=collabora.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=IcoxSeiYI5+R++Zr1B+7tAwDGkcurgAwaw/F9iiW8CI=; b=fEWCzqe9HFuDmH iuD647+crwDrd1RSkov2gym8dz1i4QAlgxWJjkkGXEQAPAh6gRdAhOSeAVitRPwTLEuOgKuWKatvV lBn+UL/wt7kPwTCX/d+O7kcH78wL6x7/c6r2JAjzNRDSWRD7oKPP3/tNAKylvYhmXUd75plnynf+v jz9H75iz2abNGrxZmz14ltA/6I7ylfPydXePTOdeVZnQ3eTK4fh+ks2TKsGObxUwPF6LeT9ykd/0S wgbBsYR5x8C4ZT5BqSmRAOPDLLCXFqp7g+jt2Y5uJ7P40+9A4zU070Trso23yygXhGhRT+Zz35jDU XUpVR6ThCSQ8NsjWBWRw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hFvp5-0007MX-6U; Mon, 15 Apr 2019 07:14:35 +0000 Received: from bhuna.collabora.co.uk ([2a00:1098:0:82:1000:25:2eeb:e3e3]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1hFvoy-0007GU-17; Mon, 15 Apr 2019 07:14:29 +0000 Received: from localhost (unknown [IPv6:2a01:e0a:2c:6930:5cf4:84a1:2763:fe0d]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: bbrezillon) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id D947528159D; Mon, 15 Apr 2019 08:14:23 +0100 (BST) Date: Mon, 15 Apr 2019 09:14:20 +0200 From: Boris Brezillon To: Miquel Raynal Subject: Re: [PATCH 2/3] mtd: rawnand: sunxi: Add DMA support for sun8i Message-ID: <20190415091420.3fb86ef7@collabora.com> In-Reply-To: <20190415085859.21f69396@xps13> References: <20190404162111.22618-1-miquel.raynal@bootlin.com> <20190404162111.22618-3-miquel.raynal@bootlin.com> <20190414110549.5c91829d@collabora.com> <20190415085859.21f69396@xps13> Organization: Collabora X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190415_001428_197993_532C64F9 X-CRM114-Status: GOOD ( 24.13 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , devicetree@vger.kernel.org, Vignesh Raghavendra , Tudor Ambarus , Maxime Ripard , Richard Weinberger , Marek Vasut , Chen-Yu Tsai , Rob Herring , linux-mtd@lists.infradead.org, Brian Norris , David Woodhouse , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-mtd" Errors-To: linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org On Mon, 15 Apr 2019 08:58:59 +0200 Miquel Raynal wrote: > Hi Boris, > > Boris Brezillon wrote on Sun, 14 Apr > 2019 11:05:49 +0200: > > > On Thu, 4 Apr 2019 18:21:10 +0200 > > Miquel Raynal wrote: > > > > > Allwinner NAND controllers can make use of DMA to enhance the I/O > > > throughput thanks to ECC pipelining. DMA handling with sun8i NAND IP > > > is a bit different than with the older SoCs, hence the introduction of > > > a new compatible to handle: > > > * the differences between register offsets, > > > * the burst length change from 4 to minimum 8, > > > * drive SRAM accesses through the AHB bus instead of the MBUS. > > > > Hm, now that you know MBUS accesses are working fine (IIRC, that's what > > you used for the SPL DMA-based implementation), why not directly use > > MBUS accesses on A33? I mean, it's likely faster than going through > > the DMA engine (which is shared by several IPs), and AFAIR, the MBUS > > setup is pretty simple. > > Because all the driver is already in shape to use the external DMA > engine and it was very easy and quick (have a look at the diff of the > v3) to use it again. Yes, I see that. I might be wrong but I'd expect the MDMA version to be just as simple as this one. > > However, the choice I am describing here is not DMA vs. MBUS (or MDMA), > it is MBUS vs. AHB, it is just about the bus that will access the SRAM > (this is what we have understood with Maxime from the datasheets and > the tests we have done). Yes, sorry, I meant MDMA vs shared DMA engine, but I guess MBUS is only used through MDMA accesses anyway, right? > For this choice, we tested with both buses: no > throughput change so we think that it is not a bottleneck anyway. Well, you'd need to test with a lot of traffic going through the DMA engine to check if that makes a difference. Anyway, it was just a suggestion, keep it like that if you think using MDMA is not worthwhile. ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/