On Mon, Jan 09, 2012 at 02:00:47PM -0800, Keith Packard wrote: > On Thu, 5 Jan 2012 23:11:53 +0100, Daniel Vetter <daniel.vetter at ffwll.ch> wrote: > > > With the new ducttape of much finer quality, this seems to be no > > longer necessary. > > > > Tested on my ivb and snb machine with the usual suspects of testcases. > > Eric suggested that unless we have evidence that the new work-around > fixes bugs on SNB, that we should continue to use the HWSTAM work-around > on that chip and use the RC6 voodoo on IVB, thus not potentially causing > regressions on SNB. > > For back-porting to older kernels, that's obviously the right plan. I > think it's also the right plan for newer kernels, but I'd love to hear > alternate views on the matter. I honestly don't trust my patch, so I'd like to give it as much validation as possible. Which means: - Shove it into -next and beat on it there. We can ship current 3.3 with Eric's workaround - it's not great but at least this works. - Enable the voodoo and revert the HWSTAM w/a also on snb - there are orders more snb machines in the wild than pre-production ivbs. I.e. this hopefully greatly increases our changes to find out whether the voodoo really works or if it is only pretty decent, but not perfect ducttape. - See what happens and act accordingly (maybe reinstate the HWSTAM w/a if it's required). If things really work out when this hits mainline, backport the voodoo patch, leaving the HWSTAM in place for older kernels. Yep, I'm officially paranoid about this ;-) rc6, forcewake and friends have simply blown up too often in unpredictable ways ... -Daniel -- Daniel Vetter Mail: daniel at ffwll.ch Mobile: +41 (0)79 365 57 48
