point()/unpoint() questions + small cfi_cmdset_0001.c patch

[Joakim Tjernlund]

> 
> joakim.tjernlund at lumentis.se said:
> >  I am mainly interested in using point() in scan.c to reduce mount
> > time. A quick and dirty hack to impl. point() gives me better a scan
> > time, from 4.43 sec to 3.53 sec, but this will probably go up a bit if
> > I do a proper impl. of point(). 
> 
> Is this on your board with burst reads working? Are you using a cached 
> mapping for point()? 

Yes x 2

> 
> >  They do? I have not seen any evidence of this, do you happen to known
> > any perticular AMD device that does this? 
> 
> Looking at the AM29LV320D datasheet, page 26, under 'Sector Erase Command 
> Sequence'...
> 
> "Note that while the Embedded Erase operation is in progress, the system can
> read data from the non-erasing sector. The system can determine the status
> of the erase operation by reading DQ7, DQ6, DQ2 or RY/BY# in the erasing
> sector."
> 
> (http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/23579a3.pdf)
> 
> OTOH, the next page talks about the Erase Suspend command, which "allows 
> the system to interrupt a sector erase operation and then read data from, 
> or program data to, any sector not selected for erasure." So perhaps I was 
> imagining it.
> 

After a quick read I think it's NOT possible to read data without suspending an Erase
first.

     Jocke