Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Mon, 17 Dec 2018 17:41:14 +0100
From:   Miquel Raynal <miquel.raynal@bootlin.com>
To:     Naga Sureshkumar Relli <nagasure@xilinx.com>
Cc:     Boris Brezillon <boris.brezillon@bootlin.com>,
        "robh@kernel.org" <robh@kernel.org>,
        "richard@nod.at" <richard@nod.at>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "marek.vasut@gmail.com" <marek.vasut@gmail.com>,
        "linux-mtd@lists.infradead.org" <linux-mtd@lists.infradead.org>,
        "nagasuresh12@gmail.com" <nagasuresh12@gmail.com>,
        Michal Simek <michals@xilinx.com>,
        "computersforpeace@gmail.com" <computersforpeace@gmail.com>,
        "dwmw2@infradead.org" <dwmw2@infradead.org>
Subject: Re: [LINUX PATCH v12 3/3] mtd: rawnand: arasan: Add support for
 Arasan NAND Flash Controller
Message-ID: <20181217174114.24196d17@xps13>
In-Reply-To: <MWHPR02MB26235AE6567A06EF4C6362E6AFBC0@MWHPR02MB2623.namprd02.prod.outlook.com>
References: <1541739641-17789-1-git-send-email-naga.sureshkumar.relli@xilinx.com>
        <MWHPR02MB26234433484426F333E9B60EAFDC0@MWHPR02MB2623.namprd02.prod.outlook.com>
        <20181118204324.373ca9cc@bbrezillon>
        <MWHPR02MB2623AAEC160F40F061E23194AFD80@MWHPR02MB2623.namprd02.prod.outlook.com>
        <20181119090246.49060019@bbrezillon>
        <BN6PR02MB2610C7D048E4A192E041BE14AFD90@BN6PR02MB2610.namprd02.prod.outlook.com>
        <20181120120244.7d2442b5@bbrezillon>
        <20181120133624.3fa4742d@xps13>
        <MWHPR02MB26238A2271B33470ABFA1023AFD40@MWHPR02MB2623.namprd02.prod.outlook.com>
        <MWHPR02MB26239C2B2A7050310BEF1E9CAFA70@MWHPR02MB2623.namprd02.prod.outlook.com>
        <20181212091135.1d0cc9a6@xps13>
        <MWHPR02MB26236CEF8A2110B20C825198AFA70@MWHPR02MB2623.namprd02.prod.outlook.com>
        <20181212100931.149b0cac@xps13>
        <MWHPR02MB2623EDA15BE59304795F3034AFA70@MWHPR02MB2623.namprd02.prod.outlook.com>
        <20181212141825.69711c57@xps13>
        <MWHPR02MB26235AE6567A06EF4C6362E6AFBC0@MWHPR02MB2623.namprd02.prod.outlook.com>
Organization: Bootlin
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8BIT
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi Naga,

[...]

> Inserted biterror @ 48/7
> Successfully corrected 25 bit errors per subpage
> Inserted biterror @ 50/7
> ECC failure, invalid data despite read success
> root@xilinx-zc1751-dc2-2018_1:~#
> 
> But even in this case also, driver is saying ECC failure but read success.
> That means controller is able to detect errors on read page up to 24 bit only.
> After that there is no way to say to the upper layers that the page is bad because of the limitation in the controller.

This is more than a "limitation", the design is broken. I am not sure
how to support such controller, and I am not sure if we even want to.

> Could you please suggest any alternative to report the errors in that case?

Shall we support the controller without the hw ECC engine? Boris, any
thoughts?


Thanks,
Miquèl