[PATCH] mtd: nand-imx: repair reading the oob area

[Sascha Hauer]

On Thu, Oct 22, 2020 at 02:25:22PM +0200, Uwe Kleine-König wrote:
> After sending the READOOB command the core (in nand_read_oob_std()) uses
> the read_buf callback to fetch the result. So in the imx driver it is
> necessary to emit the NFC_OUTPUT command to make the controller actually
> read the requested data into the internal buffer and then copy the data
> to the location where read_buf expects it.
> 
> This fixes reading from /dev/nand0.oob and also (somewhat) reading bad
> block markers in the absence of a bad block table.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig at pengutronix.de>
> ---
> Hello,
> 
> I failed to find the commit that broke reading from /dev/nand0.oob but
> failed to identify it. I think this bug is quite old. I didn't test, but
> I think this was already broken in 2010.09.0 where the nand support was
> moved from drivers/nand to drivers/mtd/nand. (This is where gitk output
> ended :-)
> 
> Best regards
> Uwe

Tested on i.MX27 and applied, thanks

Sascha

> 
>  drivers/mtd/nand/nand_imx.c | 15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mtd/nand/nand_imx.c b/drivers/mtd/nand/nand_imx.c
> index d69a012f017b..f9d3c2e34a99 100644
> --- a/drivers/mtd/nand/nand_imx.c
> +++ b/drivers/mtd/nand/nand_imx.c
> @@ -996,14 +996,23 @@ static void imx_nand_command(struct mtd_info *mtd, unsigned command,
>  		else
>  			host->buf_start = column + mtd->writesize;
>  
> -		command = NAND_CMD_READ0;
> -
> -		host->send_cmd(host, command);
> +		host->send_cmd(host, NAND_CMD_READ0);
>  		mxc_do_addr_cycle(mtd, column, page_addr);
>  
>  		if (host->pagesize_2k)
>  			/* send read confirm command */
>  			host->send_cmd(host, NAND_CMD_READSTART);
> +
> +		/*
> +		 * After the core issued READOOB the result is read using
> +		 * .read_buf, so we have to make sure the data is actually
> +		 * there.
> +		 */
> +		if (command == NAND_CMD_READOOB) {
> +			host->send_page(host, NFC_OUTPUT);
> +			copy_spare(mtd, 1, host->data_buf + mtd->writesize);
> +		}
> +
>  		break;
>  
>  	case NAND_CMD_SEQIN:
> -- 
> 2.28.0
> 
> 
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