cfi_cmdset_0001 get_chip()put_chip() contender/loaner, what does it do?

[Joakim Tjernlund]

On Tue, 2007-06-12 at 11:45 -0400, Nicolas Pitre wrote:
> On Tue, 12 Jun 2007, Joakim Tjernlund wrote:
> 
> > On Tue, 2007-06-12 at 10:50 -0400, Nicolas Pitre wrote:
> > > On Tue, 12 Jun 2007, Joakim Tjernlund wrote:
> > > 
> > > > In the beginning of get_chip() and put_chip for the cfi_cmdset_0001
> > > > driver there is this "fight" over access to the chip that I don't
> > > > understand. Why is it there and why don't the other drivers need it?
> > > 
> > > It is there to support the Intel Sibley NOR flash chips which have the 
> > > ability to allow read operations in many part of the chip at the same 
> > > time as an erase or a write operation taking place in another part of 
> > > the chip.  The erase and write operation, though, cannot have more than 
> > > one instance on the whole chip.
> > > 
> > > To facilitate the driver implementation, the Sibley flash is subdivided 
> > > in many "chips" corresponding to those parts mentioned above.  However, 
> > > since the ability to write is shared amongst all those "chips" then it 
> > > sometimes must be obtained from another chip.  The other chip might 
> > > concede it or it might not.  That's the "fighting".
> > 
> > I see, the reason for me asking about this is that I am seeing some
> > very long stalls, see the "JFFS2 appears to "freeze" during erase,
> > version 2" thread and I am starting to suspect the above mentioned code,
> > mostly because I don't understand this code and don't know where else
> > to look. Do you see anything that could explain what I am seeing?
> 
> Do you have Sibley flash?
> 
> If no then chip->priv will be false and you need no worry about that 
> code.

Oops, no. Didn't get that far. Back to the driver then, I just can't see
whats cuasing such long stalls. Its like fw_printenv is put to sleep
and then noone wakes it up.

> 
> If you do have Sibley flash then I strongly suggest that you go have a 
> look at its data sheet to understand how it works.
> 
> 
> Nicolas
>