linux-kernel - Re: [PATCH v3 5/5] mtd: rawnand: brcmnand: Fix mtd oobsize

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Message-ID: <20230704173047.395e445e@xps-13>
Date:   Tue, 4 Jul 2023 17:30:47 +0200
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     William Zhang <william.zhang@...adcom.com>
Cc:     Broadcom Kernel List <bcm-kernel-feedback-list@...adcom.com>,
        Linux MTD List <linux-mtd@...ts.infradead.org>,
        f.fainelli@...il.com, rafal@...ecki.pl, kursad.oney@...adcom.com,
        joel.peshkin@...adcom.com, computersforpeace@...il.com,
        anand.gore@...adcom.com, dregan@...l.com, kamal.dasu@...adcom.com,
        tomer.yacoby@...adcom.com, dan.beygelman@...adcom.com,
        Frieder Schrempf <frieder.schrempf@...tron.de>,
        linux-kernel@...r.kernel.org,
        Vignesh Raghavendra <vigneshr@...com>,
        Richard Weinberger <richard@....at>,
        Boris Brezillon <bbrezillon@...nel.org>,
        Kamal Dasu <kdasu.kdev@...il.com>
Subject: Re: [PATCH v3 5/5] mtd: rawnand: brcmnand: Fix mtd oobsize

Hi William,

william.zhang@...adcom.com wrote on Tue, 27 Jun 2023 12:37:38 -0700:

> brcmnand controller can only access the flash spare area up to certain
> bytes based on the ECC level. It can be less than the actual flash spare
> area size. For example, for many NAND chip supporting ECC BCH-8, it has
> 226 bytes spare area. But controller can only uses 218 bytes. So brcmand
> driver overrides the mtd oobsize with the controller's accessible spare
> area size. When the nand base driver utilizes the nand_device object, it
> resets the oobsize back to the actual flash spare aprea size from
> nand_memory_organization structure and controller may not able to access
> all the oob area as mtd advises.
> 
> This change fixes the issue by overriding the oobsize in the
> nand_memory_organization structure to the controller's accessible spare
> area size.

I am clearly not a big fan of this solution. memorg should be and
remain a read only object. Can you please find another solution?

> 
> Fixes: a7ab085d7c16 ("mtd: rawnand: Initialize the nand_device object")
> Signed-off-by: William Zhang <william.zhang@...adcom.com>
> 
> ---
> 
> Changes in v3: None
> Changes in v2: None
> 
>  drivers/mtd/nand/raw/brcmnand/brcmnand.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/brcmnand/brcmnand.c b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> index 407bf79cbaf4..39c7f547db1f 100644
> --- a/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> +++ b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> @@ -2647,6 +2647,8 @@ static int brcmnand_setup_dev(struct brcmnand_host *host)
>  	struct nand_chip *chip = &host->chip;
>  	const struct nand_ecc_props *requirements =
>  		nanddev_get_ecc_requirements(&chip->base);
> +	struct nand_memory_organization *memorg =
> +		nanddev_get_memorg(&chip->base);
>  	struct brcmnand_controller *ctrl = host->ctrl;
>  	struct brcmnand_cfg *cfg = &host->hwcfg;
>  	char msg[128];
> @@ -2668,10 +2670,11 @@ static int brcmnand_setup_dev(struct brcmnand_host *host)
>  	if (cfg->spare_area_size > ctrl->max_oob)
>  		cfg->spare_area_size = ctrl->max_oob;
>  	/*
> -	 * Set oobsize to be consistent with controller's spare_area_size, as
> -	 * the rest is inaccessible.
> +	 * Set mtd and memorg oobsize to be consistent with controller's
> +	 * spare_area_size, as the rest is inaccessible.
>  	 */
>  	mtd->oobsize = cfg->spare_area_size * (mtd->writesize >> FC_SHIFT);
> +	memorg->oobsize = mtd->oobsize;
>  
>  	cfg->device_size = mtd->size;
>  	cfg->block_size = mtd->erasesize;


Thanks,
Miquèl