Re: [PATCH] mtd: spi-nor: read 6 bytes for the ID

[Huang Shijie <b32955@freescale.com>]

On Thu, Apr 17, 2014 at 01:23:31AM +0200, Marek Vasut wrote:
> On Wednesday, April 16, 2014 at 03:56:43 PM, Huang Shijie wrote:
> > On Wed, Apr 16, 2014 at 12:18:28PM +0200, Marek Vasut wrote:
> > > On Wednesday, April 16, 2014 at 03:52:03 AM, Huang Shijie wrote:
> > > 
> > > [...]
> > > 
> > > > > > Does the chip vendor so silly to produce such chips? :)
> > > > > 
> > > > > I don't quite understand the meaning of this sentence, but the
> > > > > approach where we try heuristics doesn't scale.
> > > > 
> > > > If two chips share the same jedec_id, it means the two chips are
> > > > produced from the same chip vendor, such as 0x012018 means the chip is
> > > > from Spansion.
> > > > 
> > > > If two chips share the same 5 bytes ID, the two chips definitely are
> > > > produced from the same vendor.
> > > > 
> > > > So my meaning is the case what are you mentioned will _not_ exit in the
> > > > real world. Spansion will not so silly.
> > > 
> > > You do have an awful amount of trust for those things. I am better of
> > > with "better safe than sorry".
> > 
> > okay.
> > 
> > > > > > > This code should be future-proof, but if we keep adding such
> > > > > > > special cases, we will end up with false matches sooner or later
> > > > > > > anyway I'm
> > > > > > > 
> > > > > > > afraid.
> > > > > > > 
> > > > > > > What do you say we add the READID length field into the table ?
> > > > > > 
> > > > > > If we add the length field into the table, we have to sort the
> > > > > > table by some kind of order.
> > > > > 
> > > > > Why, please elaborate.
> > > > 
> > > > pleas see:
> > > > http://lists.infradead.org/pipermail/linux-mtd/2013-December/050670.htm
> > > > l
> > > 
> > > Sorry, but this really doesn't answer my question. It's only a matter of
> > > correctly implementing the matching function to find a proper match.
> > > 
> > > Can we get insight on this from the others please ?
> > > 
> > > > If you are interested in this issue, please give us a patch.
> > > > What I want is making the kernel can support the s25fl128s as soon as
> > > > possible.
> > > 
> > > Perfect, I'd prefer to support it as correctly as possible.
> > 
> > wait for your patch.
> 
> Please keep the discussion professional and avoid threats.
> 
Please do not make mistake about me. :) it is not a threat.

If add the readid length field to the table, i will implement nearly the
same code as Clark did. I thought You have a better idea maybe.



thanks
Huang Shijie