[PATCH] fix ehci alignment error

Greg KH [off-list ref] writes:

On Mon, Oct 10, 2011 at 07:31:26PM +0200, Mikael Pettersson wrote:

quoted

Greg KH writes:
 > On Mon, Oct 10, 2011 at 05:29:13PM +0100, M?ns Rullg?rd wrote:
 > > Greg KH [off-list ref] writes:
 > > 
 > > > On Mon, Oct 10, 2011 at 02:38:27PM +0200, Harro Haan wrote:
 > > >> The Kirkwood gave an unaligned memory access error on
 > > >> line 742 of drivers/usb/host/echi-hcd.c:
 > > >> "ehci->last_periodic_enable = ktime_get_real();"
 > > >
 > > > What is "The Kirkwood"?  What size processor is this?
 > > 
 > > It's an ARM926-like CPU from Marvell.
 > 
 > 32 or 64bit?

All ARMs are 32-bit, but some have instructions for loading or
storing 2 x 32 bits at a time, but also require the corresponding
memory address to be 64-bit aligned.

To be perfectly accurate, all ARMs have the dual load/store instructions,
but only some (ARMv5 and earlier) require a 64-bit aligned address for
these.  The Kirkwood is an ARMv5 so it does need this alignment.

Furthermore, the standard ARM ABI requires 8-byte alignment for 64-bit
data types regardless of CPU version, which is perhaps a bit unusual for
a 32-bit architecture.

-- 
M?ns Rullg?rd
mans at mansr.com