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List:       linux-sparc
Subject:    Re: javastation krups mtd patch detecting wrong amount of flash
From:       Jasper van der Neut <jvanderneut () home ! nl>
Date:       2003-04-14 8:23:03
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On Wed, Apr 02, 2003 at 07:59:01AM +0300, Jarno Manninen wrote:

> > If I erase the a partition, copy a jffs2 image to it, I get CRC errors when
> > I mount it. When I mount an empty jffs2 partition, it already has used
> > blocks, which, I think, is not normal.
> 
> At least to my experience you have to mount and unmount jffs2 partition after 
> writing its initial content. Jffs2 then "fills" or "scans"  the whole 
> partition for it's use. 

It seems jffs2 reads from flash in blocks of any size, not just a multiple
of 4. With the modification below, the jffs2 filesystem works, no more CRC
errors.

[snip] 

> diff -urN -X dontdiff linux-2.4.20/drivers/mtd/maps/jsflash.c 

[snip]

> +static void jsflash_copy_from(struct map_info *map, void *to,
> +	unsigned long from, ssize_t len)
> +{
> +	union byte4 {
> +		char s[4];
> +		unsigned int n;
> +	} b;
> +
> +	while (len >= 4) {
> +		len -= 4;
> +		b.n = jsflash_read32(map, from);
> +		memcpy(to, b.s, 4);
> +		from += 4;
> +		to += 4;
> +	}

	if (len > 0) {
		b.n = jsflash_read32(map, from);
		memcpy(to, b.s, len);
	}
> +}


Jasper
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