linux-kernel - Re: [PATCH] - change calculating of position page containing BBM

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Date:   Thu, 19 Sep 2019 14:58:19 +0200
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Piotr Sroka <piotrs@...ence.com>
Cc:     Richard Weinberger <richard@....at>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        Vignesh Raghavendra <vigneshr@...com>,
        Boris Brezillon <bbrezillon@...nel.org>,
        Frieder Schrempf <frieder.schrempf@...tron.de>,
        <linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] - change calculating of position page containing BBM

Hi Piotr,

Piotr Sroka <piotrs@...ence.com> wrote on Thu, 19 Sep 2019 13:41:35
+0100:

> Change calculating of position page containing BBM
> 
> If none of BBM flags is set then function nand_bbm_get_next_page 
> reports EINVAL. It causes that BBM is not read at all during scanning
> factory bad blocks. The result is that the BBT table is build without 
> checking factory BBM at all. For Micron flash memories none of this 
> flag is set if page size is different than 2048 bytes.

"none of these flags are set"

> 
> This patch changes the nand_bbm_get_next_page function.

"Address this regression by changing the
nand_bbm_get_next_page_function."

> It will return 0 if none of BBM flag is set and page parameter is 0. 

                      no BBM flag is set

> After that modification way of discovering factory bad blocks will work 
> similar as in kernel version 5.1.
> 

Fixes + stable tags would be great!

> Signed-off-by: Piotr Sroka <piotrs@...ence.com>
> ---
>  drivers/mtd/nand/raw/nand_base.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
> index 5c2c30a7dffa..f64e3b6605c6 100644
> --- a/drivers/mtd/nand/raw/nand_base.c
> +++ b/drivers/mtd/nand/raw/nand_base.c
> @@ -292,12 +292,16 @@ int nand_bbm_get_next_page(struct nand_chip *chip, int page)
>  	struct mtd_info *mtd = nand_to_mtd(chip);
>  	int last_page = ((mtd->erasesize - mtd->writesize) >>
>  			 chip->page_shift) & chip->pagemask;
> +	unsigned int bbm_flags = NAND_BBM_FIRSTPAGE | NAND_BBM_SECONDPAGE
> +		| NAND_BBM_LASTPAGE;
>  
> +	if (page == 0 && !(chip->options & bbm_flags))
> +		return 0;
>  	if (page == 0 && chip->options & NAND_BBM_FIRSTPAGE)
>  		return 0;
> -	else if (page <= 1 && chip->options & NAND_BBM_SECONDPAGE)
> +	if (page <= 1 && chip->options & NAND_BBM_SECONDPAGE)
>  		return 1;
> -	else if (page <= last_page && chip->options & NAND_BBM_LASTPAGE)
> +	if (page <= last_page && chip->options & NAND_BBM_LASTPAGE)
>  		return last_page;
>  
>  	return -EINVAL;

Lookgs good otherwise.

Thanks,
Miquèl