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 3D36DC433F5 for ; Tue, 28 Aug 2018 13:21:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F39D62087E for ; Tue, 28 Aug 2018 13:21:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F39D62087E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=amlogic.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 S1728139AbeH1RNJ (ORCPT ); Tue, 28 Aug 2018 13:13:09 -0400 Received: from mail-sz2.amlogic.com ([211.162.65.114]:56048 "EHLO mail-sz2.amlogic.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727209AbeH1RNJ (ORCPT ); Tue, 28 Aug 2018 13:13:09 -0400 Received: from [10.28.18.79] (10.28.18.79) by mail-sz2.amlogic.com (10.28.11.6) with Microsoft SMTP Server (TLS) id 15.0.1320.4; Tue, 28 Aug 2018 21:21:48 +0800 Subject: Re: [RFC PATCH v2 2/2] mtd: rawnand: meson: add support for Amlogic NAND flash controller To: Boris Brezillon CC: Yixun Lan , , Rob Herring , Neil Armstrong , Martin Blumenstingl , Richard Weinberger , , Marek Vasut , Jian Hu , Kevin Hilman , Carlo Caione , , Brian Norris , David Woodhouse , , Jerome Brunet References: <20180719094612.5833-1-yixun.lan@amlogic.com> <20180719094612.5833-3-yixun.lan@amlogic.com> <20180801235045.5b4d8211@bbrezillon> <42877a0d-9830-0626-3f64-e49a326eaa3c@amlogic.com> <20180817155608.5929b37a@bbrezillon> <96e538a5-1232-11f2-8b9e-5ddb09dcc2de@amlogic.com> <20180824144810.31c929a5@bbrezillon> From: Liang Yang Message-ID: Date: Tue, 28 Aug 2018 21:21:48 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:60.0) Gecko/20100101 Thunderbird/60.0 MIME-Version: 1.0 In-Reply-To: <20180824144810.31c929a5@bbrezillon> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.28.18.79] X-ClientProxiedBy: mail-sz2.amlogic.com (10.28.11.6) To mail-sz2.amlogic.com (10.28.11.6) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Boris, On 8/24/2018 8:48 PM, Boris Brezillon wrote: > On Wed, 22 Aug 2018 22:08:42 +0800 > Liang Yang wrote: > >>> You have to wait tWB, that's for sure. >>> >> we have a maximum 32 commands fifo. when command is written into >> NFC_REG_CMD, it doesn't mean that command is executing right now, maybe >> it is buffering on the queue.Assume one ERASE operation, when 2nd >> command(0xd0) is written into NFC_REG_CMD and then come into >> NAND_OP_WAITRDY_INSTR, if I read the RB status by register, it may be >> wrong because 0xd0 may not being executed. it is unusual unless >> buffering two many command. > > You should flush the queue and wait for it to empty at the end of > ->exec_op(). > >> so it seems that i still need to use nand_soft_waitrdy or wait cmd is >> executed somewhere. > > Don't you have a WAIT_FOR_RB instruction? What is NFC_CMD_RB for? Also, > NFC_CMD_IDLE seems to allow you to add an arbitrary delay, and that's > probably what you should use for tWB. > > em, I can wait for RB by reading the status from register now. but when calling nand_soft_waitrdy, i really met a problem. One *jiffies* is about 4ms. When programming, it pass 1ms to instr->ctx.waitrdy.timeout_ms and nand_soft_waitrdy will be only one *jiffies* to reach timeout. And then calling nand_soft_waitrdy maybe at the tail of 4ms interval, it may only wait 100us and next jiffies arrive. Is it correct? >