From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mail.bootlin.com ([62.4.15.54])
 by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux))
 id 1fg58o-0002n3-3w
 for linux-mtd@lists.infradead.org; Thu, 19 Jul 2018 09:22:32 +0000
Date: Thu, 19 Jul 2018 11:22:17 +0200
From: Boris Brezillon <boris.brezillon@bootlin.com>
To: Boris Brezillon <boris.brezillon@bootlin.com>, Richard Weinberger
 <richard@nod.at>, Miquel Raynal <miquel.raynal@bootlin.com>,
 linux-mtd@lists.infradead.org
Cc: David Woodhouse <dwmw2@infradead.org>, Brian Norris
 <computersforpeace@gmail.com>, Marek Vasut <marek.vasut@gmail.com>
Subject: Re: [PATCH 3/7] mtd: rawnand: Expose _notsupp() helpers for raw
 page accessors
Message-ID: <20180719112217.592b6484@bbrezillon>
In-Reply-To: <20180718084221.27821-3-boris.brezillon@bootlin.com>
References: <20180718084221.27821-1-boris.brezillon@bootlin.com>
 <20180718084221.27821-3-boris.brezillon@bootlin.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
List-Id: Linux MTD discussion mailing list <linux-mtd.lists.infradead.org>
List-Unsubscribe: <http://lists.infradead.org/mailman/options/linux-mtd>,
 <mailto:linux-mtd-request@lists.infradead.org?subject=unsubscribe>
List-Archive: <http://lists.infradead.org/pipermail/linux-mtd/>
List-Post: <mailto:linux-mtd@lists.infradead.org>
List-Help: <mailto:linux-mtd-request@lists.infradead.org?subject=help>
List-Subscribe: <http://lists.infradead.org/mailman/listinfo/linux-mtd>,
 <mailto:linux-mtd-request@lists.infradead.org?subject=subscribe>

On Wed, 18 Jul 2018 10:42:17 +0200
Boris Brezillon <boris.brezillon@bootlin.com> wrote:

> Some implementations simply can't disable their ECC engine. Expose
> helpers returning -ENOTSUPP so that the caller knows that raw accesses
> are not supported instead of silently falling back to non-raw
> accessors.
> 
> Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
> ---
>  drivers/mtd/nand/raw/nand_base.c | 33 +++++++++++++++++++++++++++++++++
>  include/linux/mtd/rawnand.h      |  4 ++++
>  2 files changed, 37 insertions(+)
> 
> diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
> index 4fa5e20d9690..323a900f3697 100644
> --- a/drivers/mtd/nand/raw/nand_base.c
> +++ b/drivers/mtd/nand/raw/nand_base.c
> @@ -2966,6 +2966,23 @@ int nand_check_erased_ecc_chunk(void *data, int datalen,
>  }
>  EXPORT_SYMBOL(nand_check_erased_ecc_chunk);
>  
> +/**
> + * nand_read_page_raw_notsupp - dummy read raw page function
> + * @mtd: mtd info structure
> + * @chip: nand chip info structure
> + * @buf: buffer to store read data
> + * @oob_required: caller requires OOB data read to chip->oob_poi
> + * @page: page number to read
> + *
> + * Returns -ENOTSUPP unconditionally.
> + */
> +int nand_read_page_raw_notsupp(struct mtd_info *mtd, struct nand_chip *chip,
> +			       u8 *buf, int oob_required, int page)
> +{
> +	return -ENOTSUPP;
> +}
> +EXPORT_SYMBOL(nand_read_page_raw_notsupp);
> +
>  /**
>   * nand_read_page_raw - [INTERN] read raw page data without ecc
>   * @mtd: mtd info structure
> @@ -3960,6 +3977,22 @@ static int nand_read_oob(struct mtd_info *mtd, loff_t from,
>  	return ret;
>  }
>  
> +/**
> + * nand_write_page_raw - dummy raw page write function

Crap, I forgot to add the _notsupp suffix in the doc.

> + * @mtd: mtd info structure
> + * @chip: nand chip info structure
> + * @buf: data buffer
> + * @oob_required: must write chip->oob_poi to OOB
> + * @page: page number to write
> + *
> + * Returns -ENOTSUPP unconditionally.
> + */
> +int nand_write_page_raw_notsupp(struct mtd_info *mtd, struct nand_chip *chip,
> +				const u8 *buf, int oob_required, int page)
> +{
> +	return -ENOTSUPP;
> +}
> +EXPORT_SYMBOL(nand_write_page_raw_notsupp);
>  
>  /**
>   * nand_write_page_raw - [INTERN] raw page write function
> diff --git a/include/linux/mtd/rawnand.h b/include/linux/mtd/rawnand.h
> index 11c2426fc363..f60fad29eae6 100644
> --- a/include/linux/mtd/rawnand.h
> +++ b/include/linux/mtd/rawnand.h
> @@ -1681,10 +1681,14 @@ int nand_get_set_features_notsupp(struct mtd_info *mtd, struct nand_chip *chip,
>  /* Default read_page_raw implementation */
>  int nand_read_page_raw(struct mtd_info *mtd, struct nand_chip *chip,
>  		       uint8_t *buf, int oob_required, int page);
> +int nand_read_page_raw_notsupp(struct mtd_info *mtd, struct nand_chip *chip,
> +			       u8 *buf, int oob_required, int page);
>  
>  /* Default write_page_raw implementation */
>  int nand_write_page_raw(struct mtd_info *mtd, struct nand_chip *chip,
>  			const uint8_t *buf, int oob_required, int page);
> +int nand_write_page_raw_notsupp(struct mtd_info *mtd, struct nand_chip *chip,
> +				const u8 *buf, int oob_required, int page);
>  
>  /* Reset and initialize a NAND device */
>  int nand_reset(struct nand_chip *chip, int chipnr);