jedec_probe.c
Joshua Wise
joshua at joshuawise.com
Sat Jul 5 21:57:04 EDT 2003
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On Saturday 05 July 2003 7:19 pm, Eric W. Biederman wrote:
> > But IMHO it does a bad job of doing it. It needs to go through each chip
> > in order, and try each chip's unlock addresses in order, as opposed to
> > guessing at unlock addresses based on interleave and chip type.
Bah, I was just pissed off :), I meant go through each chip in the array.
> I would hate to get to the point where the order of the table entries
> matters. Magic table orders are very hard to maintain properly, and
> very easy for one inattentive update to break. jedec_probe does get
> a manufacturer id and a device id which makes it good enough that with
> a few refinements it should be able to handle this. A better
> algorithm for selecting the unlock addresses is certainly desirable,
> and now we have a test case, where it actually matters.
Right. This is what I mean - jedec_probe cannot use the generic probing
functions that assume that we can query chips by doing something like Q/R/Y,
it instead should loop.
> cfi_private in this case is more badly named then anything. It holds
> generic parameters that describe NOR flash devices. The history
> is that the cfi code was written first with a generic infrastructure.
Right, right - I was just confused to hell and back :)
> And then it was realized that chips that implemented the older probe
> had the same set of requirements and the same set of commands, just
> a less convenient probe method, that does not provide all of the
> information needed to use a random flash chip. Instead that
> information needs to be looked up in a table.
goto part_where_joshua_whines_about_using_generic_probing; // :)
> To clarify I meant things like the command set/chip drivers and the
> like. In particular I meant a driver for sufficiently strange
> hardware can fill in a mtd_info structure with a fully custom set
> of methods and all of the upper layers will work.
Oh, interesting.
> Hmm. I am surprised that this has problems as it looks like a pretty
> standard part. But looking at the table of commands on page 19 it
> does appear that the standard guesses we make don't seem to line up.
Indeed, I got it working over JTAG with relatively little trouble (the main
issue being that to program, it must be used in word mode.)
> Does it work if you just hard code the address in jedec_probe_chip?
> Just to confirm which piece needs to get fixed.
I'd assume that it would. Is jedec_probe_chip used anywhere other than
jedec_probe?
> Eric
~joshua
- --
Joshua Wise | www.joshuawise.com
GPG Key | 0xEA80E0B3
Quote | <lilo> I akilled *@* by mistake
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