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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 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 51037C433DB for ; Mon, 1 Feb 2021 14:19:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0B56864EA3 for ; Mon, 1 Feb 2021 14:19:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232477AbhBAOTR convert rfc822-to-8bit (ORCPT ); Mon, 1 Feb 2021 09:19:17 -0500 Received: from relay12.mail.gandi.net ([217.70.178.232]:59123 "EHLO relay12.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229785AbhBAOTP (ORCPT ); Mon, 1 Feb 2021 09:19:15 -0500 Received: from xps13 (lfbn-tou-1-972-150.w86-210.abo.wanadoo.fr [86.210.203.150]) (Authenticated sender: miquel.raynal@bootlin.com) by relay12.mail.gandi.net (Postfix) with ESMTPSA id 90F55200008; Mon, 1 Feb 2021 14:18:25 +0000 (UTC) Date: Mon, 1 Feb 2021 15:18:24 +0100 From: Miquel Raynal To: Manivannan Sadhasivam Cc: richard@nod.at, vigneshr@ti.com, boris.brezillon@collabora.com, linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, bjorn.andersson@linaro.org Subject: Re: [PATCH] mtd: rawnand: Do not check for bad block if bbt is unavailable Message-ID: <20210201151824.5a9dca4a@xps13> In-Reply-To: <20210130035412.6456-1-manivannan.sadhasivam@linaro.org> References: <20210130035412.6456-1-manivannan.sadhasivam@linaro.org> Organization: Bootlin X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Manivannan, Manivannan Sadhasivam wrote on Sat, 30 Jan 2021 09:24:12 +0530: > The bbt pointer will be unavailable when NAND_SKIP_BBTSCAN option is > set for a NAND chip. The intention is to skip scanning for the bad > blocks during boot time. I don't have the same understanding: this flag skips the bad block table scan, not the bad block scan. We do want to scan all the devices in order to construct a RAM based table. > However, the MTD core will call > _block_isreserved() and _block_isbad() callbacks unconditionally for > the rawnand devices due to the callbacks always present while collecting > the ecc stats. > > The _block_isreserved() callback for rawnand will bail out if bbt > pointer is not available. But _block_isbad() will continue without > checking for it. So this contradicts with the NAND_SKIP_BBTSCAN option > since the bad block check will happen anyways (ie., not much difference > between scanning for bad blocks and checking each block for bad ones). > > Hence, do not check for the bad block if bbt pointer is unavailable. Not checking for bad blocks at all feels insane. I don't really get the scope and goal of such change? > > Signed-off-by: Manivannan Sadhasivam > --- > drivers/mtd/nand/raw/nand_base.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c > index c33fa1b1847f..f18cd1db79a9 100644 > --- a/drivers/mtd/nand/raw/nand_base.c > +++ b/drivers/mtd/nand/raw/nand_base.c > @@ -4286,6 +4286,9 @@ static int nand_block_isbad(struct mtd_info *mtd, loff_t offs) > int chipnr = (int)(offs >> chip->chip_shift); > int ret; > > + if (!chip->bbt) > + return 0; > + > /* Select the NAND device */ > ret = nand_get_device(chip); > if (ret) Cheers, Miquèl