On Fri, Jul 12, 2013 at 01:37:28PM -0700, Ben Widawsky wrote: > On Fri, Jul 12, 2013 at 03:02:34PM +0100, Chris Wilson wrote: > > In theory, the different register blocks were meant to be only ever > > touched when holding either the struct_mutex, mode_config.lock or even a > > specific localised lock. This does not seem to be the case, and the > > hardware reacts extremely badly if we attempt to concurrently access two > > registers within the same cacheline. > > > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=63914 > > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk> > > You are crossing the point of no return here for doing this only on HSW > where the bug is known to exist. As you are the resident performance > curmudgeon I'll defer to you if that's okay or not... just pointing it > out. I looked at all the extra checks we are doing in addition to just reading/writing the register and thought it would be better to close any races there. Hence why I think this is a correctness fix above and beyond the hsw issue. -Chris -- Chris Wilson, Intel Open Source Technology Centre
