[Patch 1/1] don't suspend erase for erase in cfi_cmdset_0002

[Peter Wippich]

Hi Jocke, 

On Mon, 3 Aug 2009, Joakim Tjernlund wrote:

> Joakim Tjernlund/Transmode wrote on 03/08/2009 15:25:10:
> >
> > Peter Wippich <pewi at gw-instruments.de> wrote on 03/08/2009 15:07:30:
> > >
> > >
> > > Hi Jocke,
> > >
> > > On Mon, 3 Aug 2009, Joakim Tjernlund wrote:
> > >
> > > > linux-mtd-bounces at lists.infradead.org wrote on 03/08/2009 12:50:44:
> > > >
> > > > >
> > > > >
> > > > > Hi,
> > > > >
> > > > > came around this problem while stress testing jffs2. From time to time the
> > > > > block erase failed and the file system overflows. I don't know if there
> > > > > are any Nor chips out there which allow a new erase to start when in erase
> > > > > suspend. However, the chips on my board dont't. And even when it doesn't
> > > > > make much sense to suspend an erase operation for another erase.
> > > > >
> > > > > Patch below fixes the problem for me.
> > > > >
> > > > > Have fun and take care,
> > > > >
> > > > > Peter
> > > > >
> > > > > Signed-off-by: Peter Wippich <pewi at gw-instruments.de>
> > > > > ---
> > > > > diff -Naur a/drivers/mtd/chips/cfi_cmdset_0002.c
> > > > > b/drivers/mtd/chips/cfi_cmdset_0002.c
> > > > > --- a/drivers/mtd/chips/cfi_cmdset_0002.c   2007-07-10 20:56:30.000000000 +0200
> > > > > +++ b/drivers/mtd/chips/cfi_cmdset_0002.c   2009-08-02 19:55:34.000000000 +0200
> > > > > @@ -521,6 +521,10 @@
> > > > >     case FL_ERASING:
> > > > >        if (mode == FL_WRITING) /* FIXME: Erase-suspend-program appears broken. */
> > > > >           goto sleep;
> > > > > +      if (mode == FL_ERASING) {
> > > > > +         printk(KERN_INFO "attempt erase suspend with mode FL_ERASING\n") ;
> > > > > +         goto sleep;
> > > > > +      }
> > > > >
> > > > >        if (!(   mode == FL_READY
> > > > >              || mode == FL_POINT
> > > > >
> > > >
> > > > This change looks bogus. You are not supposed to need the extra test.
> > > > I do think this test is faulty though:
> > > >
> > > >    if (!(   mode == FL_READY
> > > >             || mode == FL_POINT
> > > >             || !cfip
> > > >             || (mode == FL_WRITING && (cfip->EraseSuspend & 0x2))
> > > >             || (mode == FL_WRITING && (cfip->EraseSuspend & 0x1)
> > > >           )))
> > > >
> > > > What happens if cfip is NULL?
> > >
> > > Checked this one. Because the Chip is jedec probed (not cfi) and there is
> > > no fixup cfip should be NULL. Then the above will evaluate to :
> > >    mode == FL_READY = FALSE
> > >    mode == FL_POINT = FALSE
> > >    !cfip       = TRUE
> > >    (next two skipped, hopefully ...... ;-)
> > >
> > > End ! TRUE = FALSE -> we will not go to sleep ! Actually, it is not quite
> > > clear to me what the intention of this expression was. But if the original
> > > intention was to only allow erase suspend when requested mode is FL_READY
> > > or FL_POINT it is obviously wrong.....
> 
> > Probably:
> > if (!cfip || !(cfip->EraseSuspend & (0x1|0x2)) ||
> >     !(mode == FL_READY || mode == FL_POINT ||
> >      (mode == FL_WRITING && (cfip->EraseSuspend & 0x2))))
> >
> > Pehaps you can remove the
> >   if (mode == FL_WRITING) /* FIXME: Erase-suspend-program appears broken. */
> >  goto sleep;
> > too? ( in a separate patch though)
> 
> Oh, you will have to fake/construct a cfip too for you JEDEC chip.
> 
>      Jocke
 
I would prefer something more readable and less tricky. How about 
something like this. 

#define ERASE_SUSPEND_NONE	0
#define ERASE_SUSPEND_READ	1
#define ERASE_SUSPEND_RW	2


if(   !( mode==FL_READY  || mode==FL_POINT) 
   ||  ( cfip && cfip->EraseSuspend==ERASE_SUSPEND_NONE)  ) 
	goto sleep ; 

For CFI probed chips or chips with fixups this will allow disabling erase 
suspend support by setting cfip->EraseSuspend an will assume at least 
erase suspend for reads on all others. 

Ciao, 

Peter   
   


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