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 5381AC468C6 for ; Thu, 19 Jul 2018 06:22:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1075A20671 for ; Thu, 19 Jul 2018 06:22:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1075A20671 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 S1730534AbeGSHDd (ORCPT ); Thu, 19 Jul 2018 03:03:33 -0400 Received: from mail.bootlin.com ([62.4.15.54]:50853 "EHLO mail.bootlin.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727336AbeGSHDc (ORCPT ); Thu, 19 Jul 2018 03:03:32 -0400 Received: by mail.bootlin.com (Postfix, from userid 110) id 01A6820766; Thu, 19 Jul 2018 08:22:01 +0200 (CEST) Received: from bbrezillon (unknown [91.160.177.164]) by mail.bootlin.com (Postfix) with ESMTPSA id 8196B2069C; Thu, 19 Jul 2018 08:22:01 +0200 (CEST) Date: Thu, 19 Jul 2018 08:22:00 +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 2/8] mtd: rawnand: ams-delta: Write protect device during probe Message-ID: <20180719082200.470ac8d1@bbrezillon> In-Reply-To: <20180718235710.18242-3-jmkrzyszt@gmail.com> References: <20180718235710.18242-1-jmkrzyszt@gmail.com> <20180718235710.18242-3-jmkrzyszt@gmail.com> 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 Thu, 19 Jul 2018 01:57:04 +0200 Janusz Krzysztofik wrote: > Initialize NWP GPIO pin low to protect the device from hazard during > probe. Release write protection as soon as the device is under > control. > > Signed-off-by: Janusz Krzysztofik > --- > drivers/mtd/nand/raw/ams-delta.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/drivers/mtd/nand/raw/ams-delta.c b/drivers/mtd/nand/raw/ams-delta.c > index 48233d638d2a..6ac38e9cfa1a 100644 > --- a/drivers/mtd/nand/raw/ams-delta.c > +++ b/drivers/mtd/nand/raw/ams-delta.c > @@ -219,8 +219,8 @@ static int ams_delta_init(struct platform_device *pdev) > > platform_set_drvdata(pdev, priv); > > - /* Set chip enabled, but */ > - priv->gpiod_nwp = devm_gpiod_get(&pdev->dev, "nwp", GPIOD_OUT_HIGH); > + /* Set chip enabled but write protected */ > + priv->gpiod_nwp = devm_gpiod_get(&pdev->dev, "nwp", GPIOD_OUT_LOW); > if (IS_ERR(priv->gpiod_nwp)) { > err = PTR_ERR(priv->gpiod_nwp); > dev_err(&pdev->dev, "NWP GPIO request failed (%d)\n", err); > @@ -267,6 +267,9 @@ static int ams_delta_init(struct platform_device *pdev) > if (err) > goto out_mtd; > > + /* As soon as the device is found, release write protection */ > + gpiod_set_value(priv->gpiod_nwp, 1); Please don't do that until we have a generic way to assert/deassert WP from the core. I agree that we shouldn't write things in the nand_scan() path, but I'd be more comfortable if the core had control on this pin just in case we ever need to disable write-protection during chip detection/initialization. > + > /* Register the partitions */ > mtd_device_register(mtd, partition_info, ARRAY_SIZE(partition_info)); > > @@ -288,6 +291,9 @@ static int ams_delta_cleanup(struct platform_device *pdev) > struct mtd_info *mtd = nand_to_mtd(&priv->nand_chip); > void __iomem *io_base = priv->io_base; > > + /* Apply write protection */ > + gpiod_set_value(priv->gpiod_nwp, 0); > + > /* Release resources, unregister device */ > nand_release(mtd); >