linux-kernel - Re: [PATCH v3 10/10] mtd: rawnand: brcmnand: allow for on-die ecc

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Date: Wed, 24 Jan 2024 18:40:27 +0100
From: Miquel Raynal <miquel.raynal@...tlin.com>
To: David Regan <dregan@...adcom.com>
Cc: dregan@...l.com, richard@....at, vigneshr@...com, robh+dt@...nel.org,
 krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
 computersforpeace@...il.com, kdasu.kdev@...il.com,
 linux-mtd@...ts.infradead.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, joel.peshkin@...adcom.com,
 tomer.yacoby@...adcom.com, dan.beygelman@...adcom.com,
 william.zhang@...adcom.com, anand.gore@...adcom.com,
 kursad.oney@...adcom.com, florian.fainelli@...adcom.com, rafal@...ecki.pl,
 bcm-kernel-feedback-list@...adcom.com, andre.przywara@....com,
 baruch@...s.co.il, linux-arm-kernel@...ts.infradead.org,
 dan.carpenter@...aro.org
Subject: Re: [PATCH v3 10/10] mtd: rawnand: brcmnand: allow for on-die ecc

Hi David,

dregan@...adcom.com wrote on Tue, 23 Jan 2024 19:04:58 -0800:

> Allow settings for on-die ecc such that if on-die ECC is selected
> don't error out but require ECC strap setting of zero
> 
> Signed-off-by: David Regan <dregan@...adcom.com>
> Reviewed-by: William Zhang <william.zhang@...adcom.com>
> ---
> Changes in v3: None
> ---
> Changes in v2:
> - Added to patch series
> ---
>  drivers/mtd/nand/raw/brcmnand/brcmnand.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/brcmnand/brcmnand.c b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> index a4e311b6798c..42526f3250c9 100644
> --- a/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> +++ b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> @@ -2727,9 +2727,11 @@ static int brcmnand_setup_dev(struct brcmnand_host *host)
>  	cfg->blk_adr_bytes = get_blk_adr_bytes(mtd->size, mtd->writesize);
>  
>  	if (chip->ecc.engine_type != NAND_ECC_ENGINE_TYPE_ON_HOST) {
> -		dev_err(ctrl->dev, "only HW ECC supported; selected: %d\n",
> -			chip->ecc.engine_type);
> -		return -EINVAL;
> +		if (chip->ecc.strength) {
> +			dev_err(ctrl->dev, "ERROR!!! HW ECC must be set to zero for non-hardware ECC; selected: %d\n",
> +				chip->ecc.strength);

Can you use a more formal string? Also clarify it because I don't
really understand what it leads to.

> +			return -EINVAL;
> +		}
>  	}
>  
>  	if (chip->ecc.algo == NAND_ECC_ALGO_UNKNOWN) {
> @@ -2797,7 +2799,11 @@ static int brcmnand_setup_dev(struct brcmnand_host *host)
>  	if (ret)
>  		return ret;
>  
> -	brcmnand_set_ecc_enabled(host, 1);
> +	if (chip->ecc.engine_type == NAND_ECC_ENGINE_TYPE_ON_DIE) {
> +		dev_dbg(ctrl->dev, "Disable HW ECC for on-die ECC\n");

Not needed.

> +		brcmnand_set_ecc_enabled(host, 0);
> +	} else
> +		brcmnand_set_ecc_enabled(host, 1);

Style is wrong, but otherwise I think ECC should be kept disabled while
not in active use, so I am a bit surprised by this line.

>  
>  	brcmnand_print_cfg(host, msg, cfg);
>  	dev_info(ctrl->dev, "detected %s\n", msg);


Thanks,
Miquèl