Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Thu, 8 Apr 2021 17:49:22 +0200
From:   Miquel Raynal <miquel.raynal@bootlin.com>
To:     Daniel Palmer <daniel@0x0f.com>
Cc:     linux-mtd@lists.infradead.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] mtd: spinand: add support for Foresee FS35ND01G-S1Y2
Message-ID: <20210408174922.55c1149f@xps13>
In-Reply-To: <CAFr9PXk-PNWBa9VPriP3nLUqdhtm6uPnbG3n4_rRCdF5YvS7OQ@mail.gmail.com>
References: <20210213095724.3411058-1-daniel@0x0f.com>
        <20210215112409.1a755bf0@xps13>
        <CAFr9PXkh+attaCc6C2UxB=qvXksWriWOaaoEndy4k6SGE0QOHQ@mail.gmail.com>
        <20210215121653.4edd86c4@xps13>
        <CAFr9PXmVehtcm6FjBqi_hmEAj1rgtxMvarisjPmWhgjruVj++Q@mail.gmail.com>
        <20210322193213.18520b9a@xps13>
        <CAFr9PX=mL9UWcr-yWbYa5NXS-R=yHeGgM+hd_MKOa2XiBUAJOQ@mail.gmail.com>
        <20210323113233.3523d66b@xps13>
        <CAFr9PX=KMZuzp61Hq=2WdHyEzE=6J7HEPWZxPs7FEqiH-G8wFw@mail.gmail.com>
        <20210323150603.6b942a60@xps13>
        <CAFr9PXntCmdrmg+i3BB1j-aY4VbE=2iqyLcoSr9cX2090jGiGQ@mail.gmail.com>
        <20210407100204.08d894ca@xps13>
        <CAFr9PXk-PNWBa9VPriP3nLUqdhtm6uPnbG3n4_rRCdF5YvS7OQ@mail.gmail.com>
Organization: Bootlin
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8BIT
Precedence: bulk

Hi Daniel,

Daniel Palmer <daniel@0x0f.com> wrote on Wed, 7 Apr 2021 21:01:01 +0900:

> Hi Miquel,
> 
> On Wed, 7 Apr 2021 at 17:02, Miquel Raynal <miquel.raynal@bootlin.com> wrote:
> > You may look at micron_8_ecc_get_status() helper to guide you. But
> > IMHO, if there are 0-3 bf, you should probably assume there were 3 bf
> > and return 3, if there were 4, return 4, if it's uncorrectable return
> > -EBADMSG otherwise -EINVAL.  
> 
> Understood.
> 
> > We should verify that this does not mess with UBI wear leveling
> > though. Please check that returning 3-bit errors no matter the
> > actual number of flipped bits does not lead UBI to move the data away
> > (I think it's fine but we need to be sure otherwise the implementation
> > proposal is not valid).  
> 
> Ok. I'm not sure how to check that yet but I'll look into it.
> 

You can probably check the threshold in sysfs
(/sys/class/mtd/mtdX/*threshold*).

Thanks,
Miquèl