linux-kernel - Re: [PATCH v2 5/6] mtd: spi-nor: simplify spi_nor_get_flash

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Message-ID: <ea3b32a8-7a1c-4a32-beb5-acc6f6435954@linaro.org>
Date: Mon, 22 Apr 2024 07:41:08 +0100
From: Tudor Ambarus <tudor.ambarus@...aro.org>
To: Michael Walle <mwalle@...nel.org>, Pratyush Yadav <pratyush@...nel.org>,
 Miquel Raynal <miquel.raynal@...tlin.com>,
 Richard Weinberger <richard@....at>, Vignesh Raghavendra <vigneshr@...com>
Cc: Ricardo Ribalda <ribalda@...nel.org>, linux-kernel@...r.kernel.org,
 linux-mtd@...ts.infradead.org
Subject: Re: [PATCH v2 5/6] mtd: spi-nor: simplify spi_nor_get_flash_info()



On 4/19/24 15:12, Michael Walle wrote:
> Rework spi_nor_get_flash_info() to make it look more straight forward
> and esp. don't return early. The latter is a preparation to check for
> deprecated flashes.
> 
> Signed-off-by: Michael Walle <mwalle@...nel.org>
> Reviewed-by: Pratyush Yadav <pratyush@...nel.org>
> ---
>  drivers/mtd/spi-nor/core.c | 45 ++++++++++++++++++--------------------
>  1 file changed, 21 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> index 4e2ae6642d4c..8e4ae1317870 100644
> --- a/drivers/mtd/spi-nor/core.c
> +++ b/drivers/mtd/spi-nor/core.c
> @@ -3294,39 +3294,36 @@ static const struct flash_info *spi_nor_match_name(struct spi_nor *nor,
>  static const struct flash_info *spi_nor_get_flash_info(struct spi_nor *nor,
>  						       const char *name)
>  {
> -	const struct flash_info *info = NULL;
> +	const struct flash_info *jinfo = NULL, *info = NULL;
>  
>  	if (name)
>  		info = spi_nor_match_name(nor, name);
> -	/* Try to auto-detect if chip name wasn't specified or not found */
> -	if (!info)
> -		return spi_nor_detect(nor);
> -
>  	/*
> -	 * If caller has specified name of flash model that can normally be
> -	 * detected using JEDEC, let's verify it.
> +	 * Auto-detect if chip name wasn't specified or not found, or the chip
> +	 * has an ID. If the chip supposedly has an ID, we also do an
> +	 * auto-detection to compare it later.
>  	 */
> -	if (name && info->id) {
> -		const struct flash_info *jinfo;
> -
> +	if (!info || info->id) {
>  		jinfo = spi_nor_detect(nor);
> -		if (IS_ERR(jinfo)) {
> +		if (IS_ERR(jinfo))
>  			return jinfo;
> -		} else if (jinfo != info) {

you can remove else if with if (jinfo != info)

> -			/*
> -			 * JEDEC knows better, so overwrite platform ID. We
> -			 * can't trust partitions any longer, but we'll let
> -			 * mtd apply them anyway, since some partitions may be
> -			 * marked read-only, and we don't want to loose that
> -			 * information, even if it's not 100% accurate.
> -			 */
> -			dev_warn(nor->dev, "found %s, expected %s\n",
> -				 jinfo->name, info->name);

keep the warning where it was
> -			info = jinfo;

move this so that it belongs to if (!info || info->id)
> -		}
>  	}
>

and then return info. Does it work?


	if (name)
		info = spi_nor_match_name(nor, name);

	if (!info || info->id) {
		jinfo = spi_nor_detect(nor);
		if (IS_ERR(jinfo))
			return jinfo;
		
		if (jinfo != info)
			dev_warn(();
		info = jinfo;
	}

	return info;

> -	return info;
> +	/*
> +	 * If caller has specified name of flash model that can normally be
> +	 * detected using JEDEC, let's verify it.
> +	 */
> +	if (info && jinfo && jinfo != info)> +		dev_warn(nor->dev, "found %s, expected %s\n",
> +			 jinfo->name, info->name);
> +
> +	/*
> +	 * JEDEC knows better, so overwrite platform ID. We can't trust
> +	 * partitions any longer, but we'll let mtd apply them anyway, since
> +	 * some partitions may be marked read-only, and we don't want to loose
> +	 * that information, even if it's not 100% accurate.
> +	 */
> +	return jinfo ?: info;