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 _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
