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

On Wed, Aug 31, 2011 at 02:43:33PM +0100, Mark Salter wrote:

On Wed, 2011-08-31 at 09:49 +0100, Will Deacon wrote:

quoted

On Wed, Aug 31, 2011 at 01:23:47AM +0100, Chen Peter-B29397 wrote:

quoted

One question: why this write buffer issue did not happen at UP ARM V7 platform, whose dma buffer
also uncache, but bufferable?

Which CPU was on this platform?

Using a 3.1.0-rc4+ kernel on a Pandaboard, and running 'hdparm -t' on a
usb disk drive, I see ~5.8MB/s read speed. Same kernel, but passing
nosmp on the commandline, I see 20.3MB/s.

Can someone explain why nosmp would make such a difference?

Oh gawd, that's horrible. I have a feeling it's probably a separate issue
though, caused by:

omap_modify_auxcoreboot0(0x200, 0xfffffdff);

in boot_secondary for OMAP. Unfortunately I have no idea what that line is
doing because it ends up talking to the secure monitor.

Will