linux-kernel - Re: [PATCH 2/3] UBI: Do not zero out EC and VID when multi-pass writes are not supported

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Date:   Tue, 3 Nov 2020 17:18:18 +0530
From:   Vignesh Raghavendra <vigneshr@...com>
To:     Pratyush Yadav <p.yadav@...com>,
        Tudor Ambarus <tudor.ambarus@...rochip.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        <linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/3] UBI: Do not zero out EC and VID when multi-pass
 writes are not supported



On 10/12/20 11:34 PM, Pratyush Yadav wrote:
> For NOR flashes EC and VID are zeroed out before an erase is issued to
> make sure UBI does not mistakenly treat the PEB as used and associate it
> with an LEB.
> 
> But on some flashes, like the Cypress Semper S28 SPI NOR flash family,
> multi-pass page programming is not allowed on the default ECC scheme.
> This means zeroing out these magic numbers will result in the flash
> throwing a page programming error.
> 
> Do not zero out EC and VID when multi-pass writes are not supported.
> 
> Signed-off-by: Pratyush Yadav <p.yadav@...com>
> ---
>  drivers/mtd/ubi/io.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/ubi/io.c b/drivers/mtd/ubi/io.c
> index 14d890b00d2c..4023fc4886e3 100644
> --- a/drivers/mtd/ubi/io.c
> +++ b/drivers/mtd/ubi/io.c
> @@ -535,7 +535,7 @@ int ubi_io_sync_erase(struct ubi_device *ubi, int pnum, int torture)
>  		return -EROFS;
>  	}
>  
> -	if (ubi->nor_flash) {
> +	if (ubi->nor_flash && !(ubi->mtd->flags & MTD_NO_MULTI_PASS_WRITE)) {
>  		err = nor_erase_prepare(ubi, pnum);
>  		if (err)
>  			return err;
> 

You may want to get rid of assertion for mtd->writesize != 1 in case of
MTD_NORFLASH.

See drivers/mtd/ubi/build.c::631

        if (ubi->mtd->type == MTD_NORFLASH) {
                ubi_assert(ubi->mtd->writesize == 1);
                ubi->nor_flash = 1;
        }

Regards
Vignesh