[PATCH] usb: ehci: make HC see up-to-date qh/qtd descriptor ASAP

On Wed, Aug 31, 2011 at 07:19:33PM +0100, Rob Herring wrote:

On 08/31/2011 12:51 PM, Will Deacon wrote:

quoted

Another thing that Marc and I tried on OMAP4 was not bringing up the secondary
CPU during boot (by commenting out most of smp_init). In this case, I/O
performance was good until we tried to online the secondary CPU. The online
failed but after that the I/O performance was certainly degraded.

Was the SCU enabled at that point? One diff between nosmp boot and
offlining the 2nd core would be that the SCU remains enabled in the
latter case. I think the SCU does not get enabled for nosmp.

Our rudimentary test (printing out the SCU control register during boot)
showed that it *was* enabled for nosmp. I think this is due to the secure
world having to do that on OMAP so it's probably not true for other
platforms.

Will