[U-Boot] [PATCH V5 1/2] MTD/SPI: introduce table driven probing

[Mike Frysinger]

On Monday, October 11, 2010 03:56:26 Reinhard Meyer wrote:
> Dear Mike Frysinger,
> 
> > On Tuesday, October 05, 2010 10:56:39 Reinhard Meyer wrote:
> >> +	/*
> >> +	 * count the number of continuation bytes, but
> >> +	 * leave at least 3 bytes to the end of the buffer untouched
> >> +	 */
> >> +	for (shift = 0, idp = idbuf;
> >> +		shift < (sizeof(idbuf) - 3) && *idp == 0x7f;
> >> +			shift++, idp++)
> >> +		;
> >> +
> >> +	/* search the table for matches in shift and id */
> >> +	for (i = 0; i < ARRAY_SIZE(flashes); i++) {
> >> +		if (flashes[i].shift == shift && flashes[i].idcode == *idp) {
> >> +			/* we have a match, call probe */
> >> +			flash = flashes[i].probe(spi, idp);
> >> +			if (flash)
> >> +				break;
> >> +		}
> >> 
> >>  	}
> > 
> > thinking about this some more, i see two problems.  (1) we've been
> > providing 4 bytes to probe funcs (like the spansion), so 3 is too small.
> >  (2) all of the probe devices today expect to get the whole idcode
> > buffer.  so if we're going to change this API, we need to fix all the
> > probe funcs too.  but that is a lot of changes to roll into one commit,
> > so let's first focus on converting to a table without changing any probe
> > semantics.
> 
> NONE of the existing functions work with expansion, so they all get the
> unshifted, full ID buffer.

err, right.   was thinking it also shifted off the manu id byte and not just 
the continuation bytes.

i'll tweak the patch i posted and pull in your ramtron patch.

> If you provide the unshifted buffer to the function, the function should
> get the shift amount as well. Otherwise the function will again have look
> how many 0x7e's to skip....

not really.  the probe funcs already know the layout of the idcode, so 
starting at a constant offset of 3 is the same as starting at 1.
-mike
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