linux-kernel - Re: [PATCH v2 3/8] mtd: spi-nor: core: Use auto-detection only once

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Message-ID: <20220321121455.bpql7x4ebhq7s36l@ti.com>
Date:   Mon, 21 Mar 2022 17:44:55 +0530
From:   Pratyush Yadav <p.yadav@...com>
To:     Tudor Ambarus <tudor.ambarus@...rochip.com>
CC:     <michael@...le.cc>, <miquel.raynal@...tlin.com>, <richard@....at>,
        <vigneshr@...com>, <linux-mtd@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <nicolas.ferre@...rochip.com>
Subject: Re: [PATCH v2 3/8] mtd: spi-nor: core: Use auto-detection only once

On 28/02/22 01:17PM, Tudor Ambarus wrote:
> In case spi_nor_match_name() returned NULL, the auto detection was
> issued twice. There's no reason to try to detect the same chip twice,
> do the auto detection only once.
> 
> Signed-off-by: Tudor Ambarus <tudor.ambarus@...rochip.com>
> ---
>  drivers/mtd/spi-nor/core.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> index f87cb7d3daab..b1d6fa65417d 100644
> --- a/drivers/mtd/spi-nor/core.c
> +++ b/drivers/mtd/spi-nor/core.c
> @@ -2894,13 +2894,15 @@ 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 *info = NULL, *detected_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)
> -		info = spi_nor_read_id(nor);
> +	if (!info) {
> +		detected_info = spi_nor_read_id(nor);
> +		info = detected_info;
> +	}
>  	if (IS_ERR_OR_NULL(info))
>  		return ERR_PTR(-ENOENT);
>  
> @@ -2908,7 +2910,7 @@ static const struct flash_info *spi_nor_get_flash_info(struct spi_nor *nor,
>  	 * If caller has specified name of flash model that can normally be
>  	 * detected using JEDEC, let's verify it.
>  	 */
> -	if (name && info->id_len) {
> +	if (name && !detected_info && info->id_len) {
>  		const struct flash_info *jinfo;
>  
>  		jinfo = spi_nor_read_id(nor);

I think the flow can be a little bit better. How about:

	if (name)
		info = spi_nor_match_name();
	
	if (!info) {
		info = spi_nor_read_id();
		if (IS_ERR_OR_NULL(info))
			return ERR_PTR(-ENOENT);

		return info;
	}

	if (name && info->id_len) {
		...
	}

-- 
Regards,
Pratyush Yadav
Texas Instruments Inc.