Re: [PATCH] mvsas: Mainly add version info to run testing process.

[Jeff Garzik <jeff@garzik.org>]

Ke Wei wrote:
> Yes,  the mvi->sas_addr array is in wire big endian format. And it
> will be written to two
> little-endian 32-bit registers after converting to little endian. So I
> think this is independent
> of system architecture.


BTW, just a reminder...  the values written by writel() [aka mw32, in 
mvsas] are converted by the API.

Thus, when writing to MMIO registers, you always pass in CPU-endian 
values, and mw32() will do the right thing regardless of platform.

Ditto for reading MMIO registers -- regardless of being on a big-endian 
or little-endian platform, the values returned are always in CPU-endian 
format.

So the typical cases where you must perform a conversion in the driver are

1) DMA memory.  You must use le32_to_cpu(), etc.  This is the most 
common case for endian conversions.

2) In rare cases, depending on your hardware, sometimes you must add a 
conversion even though you are reading data via readl() and writing via 
writel().  Often, this rare case occurs when reading data from EEPROM 
data-in registers, for example, where the EEPROM data is in big-endian 
format.

	Jeff