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=-11.8 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_GIT 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 8ED7EC54E49 for ; Sun, 10 May 2020 20:14:41 +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 64FAA206F5 for ; Sun, 10 May 2020 20:14:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="saHedKpz" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 64FAA206F5 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-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:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=tgZ3/HCL9DgjK0E9eaK7Zp6GSTxvzU3yBKkD4axyCms=; b=saHedKpzp0Iozj nNQ7VlE048cw8075iW0jRGtp+uci+E03PXqKzQlCO2PnbgwAQVWSrqiWfJ2wHwRWj4CY93DB0XD7n fPcz5hrjxbgLQseWUGlGaXKtNgNSaWgng4t6s5XW8hFsRfgL1tm4K08+ATLYJXWHVdWTlzHeuhMmd I+QGwDqsvjm97dS63a6YuiafuJVS49qJlDEb9tKTHaXQCYJV4dCy7opwD7+MaawQB7GUXzKOg+pA2 jBvlo+0M39mao5DR3THsru0QcERprJrC3LoIfCS8FIKeQr6Xz5WJDcsf7Tbx7xEI2cNHzs/TuaVod fkXx3nzuOaGeMzQaAW+A==; 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 1jXsLQ-0003N7-6c; Sun, 10 May 2020 20:14:40 +0000 Received: from relay6-d.mail.gandi.net ([217.70.183.198]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jXsDf-00025T-8Q for linux-mtd@lists.infradead.org; Sun, 10 May 2020 20:06:45 +0000 X-Originating-IP: 91.224.148.103 Received: from localhost.localdomain (unknown [91.224.148.103]) (Authenticated sender: miquel.raynal@bootlin.com) by relay6-d.mail.gandi.net (Postfix) with ESMTPSA id DAB47C0007; Sun, 10 May 2020 20:06:36 +0000 (UTC) From: Miquel Raynal To: Masahiro Yamada , linux-mtd@lists.infradead.org Subject: Re: [PATCH v2] mtd: rawnand: denali: add more delays before latching incoming data Date: Sun, 10 May 2020 22:06:35 +0200 Message-Id: <20200510200635.3080-1-miquel.raynal@bootlin.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200317071821.9916-1-yamada.masahiro@socionext.com> References: MIME-Version: 1.0 X-linux-mtd-patch-notification: thanks X-linux-mtd-patch-commit: 5756f2e8dad46eba6e2d3e530243b8eff4dd5a42 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200510_130639_441535_83261F23 X-CRM114-Status: GOOD ( 13.82 ) 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: Marek Vasut , 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 Tue, 2020-03-17 at 07:18:21 UTC, 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 > Tested-by: Marek Vasut Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git nand/next, thanks. Miquel ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/