[PATCH] usb: ehci: make HC see up-to-date qh/qtd descriptor ASAP
From: Mark Salter <hidden>
Date: 2011-08-31 15:27:50
Also in:
linux-omap
On Wed, 2011-08-31 at 16:21 +0100, Will Deacon wrote:
On Wed, Aug 31, 2011 at 02:43:33PM +0100, Mark Salter wrote:quoted
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.
Okay, I may poke around a bit with that to see I can get a better understanding. With the patched ehci-q.c, I see no noticeable difference between smp and nosmp. Both get me around 23.5MB/s with my setup. --Mark