[PATCH] mtd: cfi_cmdset_0001 - fixup for PC28F512P33TFA

[Joakim Tjernlund]

Christoph Fritz <chf.fritz at googlemail.com> wrote on 2014/04/02 01:10:30:
> 
> On Tue, 2014-04-01 at 21:13 +0200, Joakim Tjernlund wrote:
> > Christoph Fritz <chf.fritz at googlemail.com> wrote on 2014/04/01 
17:09:51:
> > > I already tried all sorts of combinations of various delays and 0xff
> > > writes, which can be used wasteful without impact. And yes, errors 
are
> > > happening less -- but are still happening (at for example -2°C 
starting
> > > udev or a filesys-bench program like bonnie++).
> > 
> > Amazing Micron still sells these defect chips
> 
> Yeah, and it was pain to do all these kinds of tests to get it reliably
> working for a real world application where minus degrees can happen. For
> me it would be no problem to keep this quirk in my private queue, but
> involving a bigger audience seems to be right considering the facts.
> 
> > > Sure, it's possible that I missed the holy right
> > > delay-0xff-quirk-combination to get this NOR flash reliable working 
for
> > > its specified temperature range. But until nobody has found it, I 
would
> > > prefer to stick to my posted quirk and just disable suspend erase.
> > 
> > Problem is, if you add that quirk no-one will be able to remove it 
later 
> > so we
> > better make sure there isn't a less intrusive solution.
> 
> What about a comment or printk which makes that clear? I anyway don't
> think that there are interested users of this specific NOR flash left
> using a current kernel -- but who knows, right.

Yes and a new commit msg which indicates you have tried all workarounds 
suggested
by Micron to no avail.

> 
> > hmm, have you checked you bus timing? Perhaps you need to relax it 
> > somewhat.
> 
> Sure, I rechecked the WEIM interface (imx35 bus) settings more than
> once. I also did testings with most relaxed settings (highest delays
> possible). But still, flash errors do occur.

Well, I am out of ideas and it seems you are too.
If not Micron comes back with a solution I guess there is no choice

> 
> I should mention that a PC28F256P33BFE (a similar 32 MB NOR flash) works
> without any quirk in all my testing environments just reliable as it
> should be.
> 
> > > Maybe someone from Micron can help?
> > 
> > Yes, you should contact them.
> 
> Is there anybody out there knowing a contact without the need of going
> through a business-ticket-support-hell ?

Sadly no.

 Jocke