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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 48126ECDFB8 for ; Fri, 20 Jul 2018 19:29:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 02F4B2064D for ; Fri, 20 Jul 2018 19:29:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 02F4B2064D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=bootlin.com 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 S2388457AbeGTUTG (ORCPT ); Fri, 20 Jul 2018 16:19:06 -0400 Received: from mail.bootlin.com ([62.4.15.54]:34826 "EHLO mail.bootlin.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388180AbeGTUTG (ORCPT ); Fri, 20 Jul 2018 16:19:06 -0400 Received: by mail.bootlin.com (Postfix, from userid 110) id C326720717; Fri, 20 Jul 2018 21:29:23 +0200 (CEST) Received: from bbrezillon (unknown [37.173.220.171]) by mail.bootlin.com (Postfix) with ESMTPSA id DB43F2069C; Fri, 20 Jul 2018 21:29:11 +0200 (CEST) Date: Fri, 20 Jul 2018 21:29:10 +0200 From: Boris Brezillon To: Janusz Krzysztofik Cc: Miquel Raynal , Tony Lindgren , Aaro Koskinen , Grygorii Strashko , Santosh Shilimkar , Kevin Hilman , Linus Walleij , Richard Weinberger , David Woodhouse , Brian Norris , Marek Vasut , linux-mtd@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org, linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, Artem Bityutskiy Subject: Re: [RFC PATCH 3/8] mtd: rawnand: ams-delta: Set port direction once per transfer Message-ID: <20180720212910.49bb2a88@bbrezillon> In-Reply-To: <90128326.sKM4evrj8F@z50> References: <20180718235710.18242-1-jmkrzyszt@gmail.com> <20180718235710.18242-4-jmkrzyszt@gmail.com> <20180719082318.290abee1@bbrezillon> <90128326.sKM4evrj8F@z50> X-Mailer: Claws Mail 3.15.0-dirty (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 20 Jul 2018 20:12:05 +0200 Janusz Krzysztofik wrote: > On Thursday, July 19, 2018 8:23:18 AM CEST Boris Brezillon wrote: > > On Thu, 19 Jul 2018 01:57:05 +0200 > > Janusz Krzysztofik wrote: > > > > > In its current shape, the driver sets data port direction before each > > > byte read/write operation, even during multi-byte transfers. Optimize > > > that by setting the port direction only on first byte of each transfer. > > > > Sounds like premature optimization for something you'll rework when > > fully switching to the GPIO consumer API to control the DATA bus. > > Indeed, this optimization was crucial for getting acceptable performance of > data transfers over GPIO. I'm only not sure if there is any action in > response to your comment expected on my side, e.g., did you want to say I > should modify the patch description, or change the order of patches? I'm just saying that, since you switch to a solution that goes through the GPIO framework to control the data bus, making sure the the pin direction change is done only once when reading/writing several bytes is something you can do after/when transitioning to the new approach. So yes, I suggest to re-order patches, except that this patch won't look the same at all if you move it after the "use the GPIO consumer API to control data bus" patch.