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=-10.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 7A929C55185 for ; Wed, 22 Apr 2020 15:30:13 +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 46DFC20776 for ; Wed, 22 Apr 2020 15:30:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Klu1LX+v" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 46DFC20776 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=denx.de 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:In-Reply-To:MIME-Version:Date: Message-ID:From:References:To:Subject:Reply-To:Content-ID:Content-Description :Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=ybgNmlv0p2ANj4vEdOFqrUY857gJnDjs4uJZRUKhlXI=; b=Klu1LX+vkVF10y j/s25xrMJu61eXj8/jYH9JsvgI2iw2G5mhMphSAP5EtUM0ZUTg5R4N/u07MgGRkXymUjQJ7vOJo9N Rb6ha0HVXtbtdZNljpKhsoj2/J7ZV7Sq2GhvuAF4PxtyYe+tUwexrOCnED3I5mTeFAVNkUC2MJQdB 82Bxg+PiDVBnQ1jf+tq5qfIZPGYV8+ySQmN+NczSTxLlYddHDShB8/fvrM8CI5GNlMaAEAFFR21s5 uo6GtodZ22VEUrJX34r0UkINvirmNa/K4wbTiNGbaZ/tDAmdW74LkD98d4mzpJOGrIsRac7DsEwGs 7Owh3YIzYEaIK6JvWmcg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jRHK5-00079O-5s; Wed, 22 Apr 2020 15:30:01 +0000 Received: from mail-out.m-online.net ([212.18.0.9]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jRHK1-00077e-UF for linux-mtd@lists.infradead.org; Wed, 22 Apr 2020 15:29:59 +0000 Received: from frontend01.mail.m-online.net (unknown [192.168.8.182]) by mail-out.m-online.net (Postfix) with ESMTP id 496krg2xvLz1qrMW; Wed, 22 Apr 2020 17:29:55 +0200 (CEST) Received: from localhost (dynscan1.mnet-online.de [192.168.6.70]) by mail.m-online.net (Postfix) with ESMTP id 496krg1fS6z1qr44; Wed, 22 Apr 2020 17:29:55 +0200 (CEST) X-Virus-Scanned: amavisd-new at mnet-online.de Received: from mail.mnet-online.de ([192.168.8.182]) by localhost (dynscan1.mail.m-online.net [192.168.6.70]) (amavisd-new, port 10024) with ESMTP id gpc7EwN5kMR7; Wed, 22 Apr 2020 17:29:53 +0200 (CEST) X-Auth-Info: VZnIEV8jQsmO1NWOjpCi2rkjveYliaMIX7iFMxDCgX0= Received: from [IPv6:::1] (unknown [195.140.253.167]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.mnet-online.de (Postfix) with ESMTPSA; Wed, 22 Apr 2020 17:29:53 +0200 (CEST) Subject: Re: [PATCH v2] mtd: rawnand: denali: add more delays before latching incoming data To: Masahiro Yamada , linux-mtd@lists.infradead.org References: <20200317071821.9916-1-yamada.masahiro@socionext.com> From: Marek Vasut Message-ID: <6093dfab-1e9e-824a-b639-33d340b377f9@denx.de> Date: Wed, 22 Apr 2020 17:29:53 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200317071821.9916-1-yamada.masahiro@socionext.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200422_082958_136099_87D27D44 X-CRM114-Status: GOOD ( 17.85 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Richard Weinberger , Vignesh Raghavendra , linux-kernel@vger.kernel.org, Miquel Raynal 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 3/17/20 8:18 AM, Masahiro Yamada wrote: > The Denali IP have several registers to specify how many clock cycles > should be waited between falling/rising signals. You can improve the > NAND access performance by programming these registers with optimized > values. > > Because struct nand_sdr_timings represents the device requirement > in pico seconds, denali_setup_data_interface() computes the register > values by dividing the device timings with the clock period. > > Marek Vasut reported this driver in the latest kernel does not work > on his SOCFPGA board. (The on-board NAND chip is mode 5) > > The suspicious parameter is acc_clks, so this commit relaxes it. > > The Denali NAND Flash Memory Controller User's Guide describes this > register as follows: > > acc_clks > signifies the number of bus interface clk_x clock cycles, > controller should wait from read enable going low to sending > out a strobe of clk_x for capturing of incoming data. > > Currently, acc_clks is calculated only based on tREA, the delay on the > chip side. This does not include additional delays that come from the > data path on the PCB and in the SoC, load capacity of the pins, etc. > > This relatively becomes a big factor on faster timing modes like mode 5. > > Before supporting the ->setup_data_interface() hook (e.g. Linux 4.12), > the Denali driver hacks acc_clks in a couple of ways [1] [2] to support > the timing mode 5. > > We would not go back to the hard-coded acc_clks, but we need to include > this factor into the delay somehow. Let's say the amount of the additional > delay is 10000 pico sec. > > In the new calculation, acc_clks is determined by timings->tREA_max + > data_setup_on_host. > > Also, prolong the RE# low period to make sure the data hold is met. > > Finally, re-center the data latch timing for extra safety. > > [1] https://github.com/torvalds/linux/blob/v4.12/drivers/mtd/nand/denali.c#L276 > [2] https://github.com/torvalds/linux/blob/v4.12/drivers/mtd/nand/denali.c#L282 > > Reported-by: Marek Vasut > Signed-off-by: Masahiro Yamada I tested it on the AV SoCFPGA, this seems to work, so feel free to apply. ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/