[PATCH 0/3] mtd: core: protect access to mtd devices while in suspend

[Sean Nyekjaer]

On Wed, Oct 20, 2021 at 09:00:58AM +0200, Boris Brezillon wrote:
> On Wed, 20 Oct 2021 08:52:50 +0200
> Boris Brezillon <boris.brezillon at collabora.com> wrote:
> 

[ ... ]
> > > 
> > > Hi Boris and Miquel,
> > > 
> > > gpmi-nand.c sets NAND_SKIP_BBTSCAN so we won't get there and populate
> > > suspend resume hooks :(
> > > Guess there is other drivers that does the same thing...  
> 
> Actually, this version is even cleaner:
> 
> diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
> index 3d6c6e880520..98c39b7f6279 100644
> --- a/drivers/mtd/nand/raw/nand_base.c
> +++ b/drivers/mtd/nand/raw/nand_base.c
> @@ -6222,8 +6222,6 @@ static int nand_scan_tail(struct nand_chip *chip)
>         mtd->_sync = nand_sync;
>         mtd->_lock = nand_lock;
>         mtd->_unlock = nand_unlock;
> -       mtd->_suspend = nand_suspend;
> -       mtd->_resume = nand_resume;
>         mtd->_reboot = nand_shutdown;
>         mtd->_block_isreserved = nand_block_isreserved;
>         mtd->_block_isbad = nand_block_isbad;
> @@ -6261,14 +6259,20 @@ static int nand_scan_tail(struct nand_chip *chip)
>                 goto err_free_interface_config;
>  
>         /* Check, if we should skip the bad block table scan */
> -       if (chip->options & NAND_SKIP_BBTSCAN)
> -               return 0;
> -
> -       /* Build bad block table */
> -       ret = nand_create_bbt(chip);
> -       if (ret)
> -               goto err_free_secure_regions;
> +       if (chip->options & NAND_SKIP_BBTSCAN) {
> +               /* Build bad block table */
> +               ret = nand_create_bbt(chip);
> +               if (ret)
> +                       goto err_free_secure_regions;
> +       }
>  
> +       /*
> +        * Populate the suspend/resume hooks after the BBT has been scanned to
> +        * avoid using the suspend lock and resume waitqueue which are only
> +        * initialized when mtd_device_register() is called.
> +        */
> +       mtd->_suspend = nand_suspend;
> +       mtd->_resume = nand_resume;
>         return 0;
>  
>  err_free_secure_regions:

Why is the gpmi-nand.c and other drivers set NAND_SKIP_BBTSCAN and then
call nand_create_bbt() directly?

To me it looks like legacy leftover...

/Sean