On Wed, May 23, 2012 at 09:07:28AM +0200, Daniel Vetter wrote: > On Wed, May 23, 2012 at 08:59:07AM +0200, Zdenek Kabelac wrote: > > Hmm I've been using i915.lvds_downclock=1 on grub command line, and > > haven't noticed any visible problems with 3.3 kernel. So I'd rather > > ask if the problematic patch isn't doing downclocking in a wrong way? > > Or maybe detection that downclocking is not supported properly is not > > correct now ? > > Nope, Sean's analysis is pretty much correct, that patch only makes > downclocking possible in more circumstances. And downclocking can > certainly explain what you're seeing, the backlight pwm signal is driven > off the panel dotclock, so if we change that we can very likely cause some > funny interference. I guess we could frob the backligth control settings > and adjust them for the change in clockspeed, but the current backlight > code is a bit a mess. So right now I suggest you just drop that option - > there are reasons it's not the default ;-) Quick question: What's the frequency of the brightness change? And how regular are the changes? -Daniel -- Daniel Vetter Mail: daniel at ffwll.ch Mobile: +41 (0)79 365 57 48
