From mboxrd@z Thu Jan 1 00:00:00 1970 From: Janusz Krzysztofik Subject: Re: [RFC PATCH 2/8] mtd: rawnand: ams-delta: Write protect device during probe Date: Fri, 20 Jul 2018 20:02:02 +0200 Message-ID: <1627187.tdZp97APJX@z50> References: <20180718235710.18242-1-jmkrzyszt@gmail.com> <20180718235710.18242-3-jmkrzyszt@gmail.com> <20180719082200.470ac8d1@bbrezillon> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: In-Reply-To: <20180719082200.470ac8d1@bbrezillon> Sender: linux-kernel-owner@vger.kernel.org To: Boris Brezillon 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 List-Id: linux-gpio@vger.kernel.org On Thursday, July 19, 2018 8:22:00 AM CEST Boris Brezillon wrote: > 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. OK, I can drop this patch for now if that's what you suggest. Thanks, Janusz