[PATCH] enable erase-suspend-program for CFI cmdset_0002

[Nicolas Pitre]

On Thu, 19 Nov 2009, Norbert van Bolhuis wrote:

> 
> erase-suspend for writing is required to avoid blocking applications that wish
> to write some data (to a NOR block other than the one being erased).
> Particularly, it solves some huge delays that an application (which writes to a
> UBIFS) will experience if UBI attaches to empty NOR flash. In this case the
> UBI background thread will erase a lot of blocks and the application can be blocked
> for minutes because of the "MTD/CFI chip lock".
> This feature has been disabled for years. Maybe this was because the old code
> turned it on for erase-suspend read-only chips also (cfip->EraseSuspend & 0x1).
> This is wrong and corrected now.
> I tested this patch and it seems to work fine.
> 
> Signed-off-by: Norbert van Bolhuis <nvbolhuis at aimvalley.nl>

FYI: I have no experience with non-Intel parts and no good knowledge of 
the cmdset_0002 code.  So I can't review this.

> ---
>  drivers/mtd/chips/cfi_cmdset_0002.c |   16 +++-------------
>  1 files changed, 3 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/mtd/chips/cfi_cmdset_0002.c b/drivers/mtd/chips/cfi_cmdset_0002.c
> index 94bb61e..1d49e18 100644
> --- a/drivers/mtd/chips/cfi_cmdset_0002.c
> +++ b/drivers/mtd/chips/cfi_cmdset_0002.c
> @@ -490,10 +490,6 @@ static struct mtd_info *cfi_amdstd_setup(struct mtd_info *mtd)
>  	}
>  #endif
>  
> -	/* FIXME: erase-suspend-program is broken.  See
> -	   http://lists.infradead.org/pipermail/linux-mtd/2003-December/009001.html */
> -	printk(KERN_NOTICE "cfi_cmdset_0002: Disabling erase-suspend-program due to code brokenness.\n");
> -
>  	__module_get(THIS_MODULE);
>  	return mtd;
>  
> @@ -589,15 +585,9 @@ static int get_chip(struct map_info *map, struct flchip *chip, unsigned long adr
>  		return 0;
>  
>  	case FL_ERASING:
> -		if (mode == FL_WRITING) /* FIXME: Erase-suspend-program appears broken. */
> -			goto sleep;
> -
> -		if (!(   mode == FL_READY
> -		      || mode == FL_POINT
> -		      || !cfip
> -		      || (mode == FL_WRITING && (cfip->EraseSuspend & 0x2))
> -		      || (mode == FL_WRITING && (cfip->EraseSuspend & 0x1)
> -		    )))
> +		if (!cfip || !(cfip->EraseSuspend & (0x1|0x2)) ||
> +		    !(mode == FL_READY || mode == FL_POINT ||
> +		    (mode == FL_WRITING && (cfip->EraseSuspend & 0x2))))
>  			goto sleep;
>  
>  		/* We could check to see if we're trying to access the sector
> -- 
> 1.5.2.2
>