From mboxrd@z Thu Jan  1 00:00:00 1970
From: Scott Wood <scottwood@freescale.com>
Date: Wed, 13 Aug 2014 17:54:53 -0500
Subject: [U-Boot] [PATCH 3/4] mtd: nand: add Freescale NFC driver
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On Wed, 2014-08-13 at 17:44 -0400, Bill Pringlemeir wrote:
> Regarding "can't know in advance", I think that some of the register
> values maybe set by the boot rom.  This might make more sense for Linux
> than U-Boot.  However, after the initial configuration, many do need the
> 'read/modify/write' as there are many bit fields with different
> functionality.

If the register is only modified by software, and not asynchronously by
hardware, then you could read the value once when the driver starts, and
cache its value to avoid a reportedly expensive I/O access every time
you need to modify it.

-Scott