at91_nand question

Ricard Wanderlof ricard.wanderlof at
Mon Feb 18 11:02:40 EST 2008

On Tue, 19 Feb 2008, Atsushi Nemoto wrote:

> Hi.  Looking at at91_nand.c, I found that this driver does not
> controls NCE signal during normal operations.  The driver only enables
> NCE on at91_nand_probe() and disables NCE on at91_nand_remove().
> Is this normal behavior?  I thought a nand driver should control NCE
> signal on cmd_ctrl routine.  If the nand driver supported only one
> chip, it can omit NCE control?
> Though it seems work fine as is, I wonder keeping chipselect signal
> low all the time is normal.

I think it is necessary for some flash chips. E.g. to erase, one cannot 
just issue an erase command and make NCE go inactive, as making NCE go 
inactive stops the erase procedure until asserted again.

Ricard Wolf Wanderlöf                           ricardw(at)
Axis Communications AB, Lund, Sweden  
Phone +46 46 272 2016                           Fax +46 46 13 61 30

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