On Thu, Jun 28, 2012 at 07:52:18AM +0200, Takashi Iwai wrote: > At Tue, 26 Jun 2012 15:08:32 -0400, > Giacomo Comes wrote: > > > > I have a dell latitude E6420 with Sandybridge Mobile (GT2). > > Since I got it (about one year ago), it has been a nightmare to run linux on it. > > At the beginning I installed openSUSE 11.4 (kernel 2.6.37.6) and the laptop > > would freeze almost immediately. After that I waited for newer kernels in order to > > see if things would improve. They did improve indeed and finally with kernel 3.0 > > I was able to run linux (openSUSE 11.4) without laptop freeze or screen issue. > > Unfortunately, the only kernel that works with my laptop is 3.0. Newer kernel > > (3.1, 3.2, 3.3 and 3.4) do not work. > > This is what happen if I run kernel 2.6.39, 3.1, 3.2, 3.3 and 3.4: > > The laptop boot and does the boot process fine. At the end of the boot process X > > starts and here the problem appears (about 50% of the times): > > the screen goes black on the left side (about 2/3 of the whole screen) with white > > stripes to the right side (the remaining 1/3). > > The laptop is not dead: I can remotely login or I can perform a clean shutdown > > if I press the power button, but the screen is totally dead. > > Another strange issue is that after a bad boot (with the black screen) at the > > next reboot the screen will start to flicker. The flickering will last some time > > and it will become less intense as the time goes until it will disappear completely. > > The funny thing is that the intensity of flicker depends on how long I keep the > > black screen. If, after the boot process, the black screen appears and I reboot > > the laptop immediately, then the flicked is moderate and it disappear after > > 1 or 2 minutes. If I keep the black screen for 1 minute or more, then after the > > reboot the flicker is very intense and it takes much more to fade. > > This reminds me of a similar bug I've seen on HP laptops with HD+ > (1600x900) monitors. Could you check whether the patch below helps? > > Note that it just avoids entering to the wrong mode. If your laptop > already starts flickering, at first recover from the flickering state, > apply the patch, and reboot/test. > > > Takashi > > --- > diff --git a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c > index 08eb04c..3f61bba 100644 > --- a/drivers/gpu/drm/i915/intel_lvds.c > +++ b/drivers/gpu/drm/i915/intel_lvds.c > @@ -413,7 +413,7 @@ static void intel_lvds_prepare(struct drm_encoder *encoder) > * the panel fitter. However at all other times we can just reset > * the registers regardless. > */ > - if (!HAS_PCH_SPLIT(encoder->dev) && intel_lvds->pfit_dirty) > + /*if (!HAS_PCH_SPLIT(encoder->dev) && intel_lvds->pfit_dirty)*/ > intel_lvds_disable(intel_lvds); > } > This patch seems to fix the problem. I will regularly run a kernel with this patch and report if I see any other issue. Giacomo
