[PATCH] Add support for flag status register on Micron chips

[grmoore at altera.com]

From: Graham Moore <grmoore at altera.com>

This is a slightly different version of the patch that Insop Song
submitted (http://marc.info/?i=201403012022.10111.marex%20()%20denx%20!%20de).

I talked to Insop, and he agreed I should submit this patch as a follow-on to his.

This patch uses a flag in the m25p_ids[] array to determine which chips need
to use the FSR (Flag Status Register).

Rationale for using the FSR:

The Micron data sheets say we have to do this, at least for the multi-die 512M 
and 1G parts (n25q512 and n25q00).  In practice, if we don't check the FSR 
for program/erase status, and we rely solely on the status register (SR), 
then we get corrupted data in the flash.

Micron told us (Altera) that for multi-die chips based on the 65nm 256MB
die, we need to check the SR first, then check the FSR, which is why the 
wait_for_fsr_ready function does that.  Future chips based on 45 nm 512MB die 
will use the FSR only.              

Thanks.

Graham Moore (1):
  Add support for flag status register on Micron chips.

 drivers/mtd/devices/m25p80.c |   94 +++++++++++++++++++++++++++++++++++-------
 1 file changed, 80 insertions(+), 14 deletions(-)

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1.7.10.4