linux-kernel - Re: [PATCH 2/4] mtd: nand: mxc_nand: implement exec

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Date: Mon, 6 May 2024 16:02:54 +0200
From: Miquel Raynal <miquel.raynal@...tlin.com>
To: Sascha Hauer <s.hauer@...gutronix.de>
Cc: Richard Weinberger <richard@....at>, Vignesh Raghavendra
 <vigneshr@...com>, linux-mtd@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] mtd: nand: mxc_nand: implement exec_op

Hi Sascha,

s.hauer@...gutronix.de wrote on Wed, 17 Apr 2024 09:13:29 +0200:

> This converts the driver to the more modern exec_op which gets us rid
> of a bunch of legacy code. Tested on i.MX27 and i.MX25.

Thanks a lot for this contribution!

> 
> Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>

..

>  static int mxc_nand_read_page_raw(struct nand_chip *chip, uint8_t *buf,
>  				  int oob_required, int page)
>  {
> +	struct mtd_info *mtd = nand_to_mtd(chip);
>  	struct mxc_nand_host *host = nand_get_controller_data(chip);
> -	void *oob_buf;
> +	int ret;
> +
> +	host->devtype_data->enable_hwecc(chip, false);

In general the expected logic would be to keep the ECC engine disabled
and just enable/use it/disable in the page helpers.

> +
> +	ret = nand_read_page_op(chip, page, 0, buf, mtd->writesize);
> +	if (ret)
> +		return ret;
>  
>  	if (oob_required)
> -		oob_buf = chip->oob_poi;
> -	else
> -		oob_buf = NULL;
> +		copy_spare(mtd, true, chip->oob_poi);
>  
> -	return host->devtype_data->read_page(chip, buf, oob_buf, 0, page);
> +	return 0;
>  }
>  

..

>  static int mxcnd_probe(struct platform_device *pdev)
> @@ -1752,13 +1594,6 @@ static int mxcnd_probe(struct platform_device *pdev)
>  
>  	nand_set_controller_data(this, host);
>  	nand_set_flash_node(this, pdev->dev.of_node);
> -	this->legacy.dev_ready = mxc_nand_dev_ready;
> -	this->legacy.cmdfunc = mxc_nand_command;
> -	this->legacy.read_byte = mxc_nand_read_byte;
> -	this->legacy.write_buf = mxc_nand_write_buf;
> -	this->legacy.read_buf = mxc_nand_read_buf;
> -	this->legacy.set_features = mxc_nand_set_features;
> -	this->legacy.get_features = mxc_nand_get_features;

Very nice diff overall. I'm fine with the first two patches, do you
mind if I merge 1 and 2 for now? We need to discuss further the subpage
issue.

As mentioned above, I would welcome a patch setting the HW ECC engine to
false by default and only enabling it in the page helpers (when using
the on-host ECC engine of course). This would be a good minor step,
with or without software ECC support.

Thanks,
Miquèl