Messages in this thread Patch in this message | | | Date | Fri, 10 Aug 2012 13:59:22 +0200 | From | Takashi Iwai <> | Subject | Re: i915 regression on 3.6-rc1: lid blanks screen |
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At Mon, 6 Aug 2012 11:25:30 -0700 (PDT), Hugh Dickins wrote: > > On Mon, 6 Aug 2012, Daniel Vetter wrote: > > On Mon, Aug 6, 2012 at 6:21 AM, Hugh Dickins <hughd@google.com> wrote: > > > On Sun, 5 Aug 2012, Takashi Iwai wrote: > > >> At Sat, 4 Aug 2012 10:01:13 -0700 (PDT), > > >> Hugh Dickins wrote: > > >> > > > >> > Sorry to report that with 3.6-rc1, closing and opening the lid on > > >> > this ThinkPad T420s leaves the screen blank, and I have to reboot. > > >> > > > >> > Bisection led to this commit, and reverting indeed gets my screen back: > > >> > > > >> > commit 520c41cf2fa029d1e8b923ac2026f96664f17c4b > > >> > Author: Daniel Vetter <daniel.vetter@ffwll.ch> > > >> > Date: Wed Jul 11 16:27:52 2012 +0200 > > >> > > > >> > drm/i915/lvds: ditch ->prepare special case > > > ... > > >> > > >> Hm, it's surprising. > > >> > > >> Could you check whether the counter-part intel_lvds_enable() is > > >> called? If the prepare callback affects, it must be from the mode > > >> setting (drm_crtc_helper_set_mode()). > > > > > > Yes, I put a dump_stack() in both, and intel_lvds_enable() gets called > > > about 0.28 seconds after the intel_lvds_disable() when I lift the lid; > > > but with no video display until I revert that commit. > > > > Can you please boot with drm.debug=0xe added to your kernel cmdline, > > reproduce the issue (with the two dump_stack calls added) and then > > attach the full dmesg? > > Collected, I'll send it to you both privately in a moment. > > > > > Also a few other things to try: What happens if you do a modeset on > > the LVDS while it's still working, e.g. > > In the dmesg, I've only gone to runlevel 3, simply working on the > console without startx. For these xrandrs to work, I did startx > and used the graphics screen.
OK, now I can see the problem here, too. The key is that it happens only on Linux console, not on X. That's why no one else reported. I guess the problem can be seen on many laptops with LVDS on PCH.
Looking at intel_reg_dumper output, BLC_PWM_CPU_CTL is 0 while other registers are set correctly. This seems coming from the rewrite of backlight control code by commit 24ded204: drm/i915: properly enable the blc controller on the right pipe and a4f32fc3: drm/i915: don't forget the PCH backlight registers
While the latter fixes the regression by the former commit, it still doesn't cover this regression.
I don't know the exact hardware behavior, but it looks like that resetting BLC_PWM_PCH_CTL2 and BLC_PWM_PCH_CTL1 clears the BLC_PWM_CPU_CTL (oh what confusing reg names).
FWIW, the commit 520c41cf you mentioned is no direct cause. This patch works fine on the top of 3.5 kernel. But it's like a bad drug, the combination of this and other two commits break things.
The patch below is my quick fix. It worked on an HP laptop. Hugh, could you give it a try?
thanks,
Takashi
=== From: Takashi Iwai <tiwai@suse.de> Subject: [PATCH] drm/i915: Fix blank panel at reopening lid on Linux console
When you reopen the lid on Linux console on a laptop with PCH, the panel suddenly goes blank. It seems because BLC_PWM_CPU_CTL register is cleared when BLC_PWM_PCH_CTL1 and BLC_PWM_PCH_CTL2 registers are played.
This patch fixes the problem by setting BLC_PWM_CPU_CTL after enabling BLC_PWM_PCH_CTL_1 and _2 registers.
Signed-off-by: Takashi Iwai <tiwai@suse.de> --- drivers/gpu/drm/i915/intel_panel.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c index 10c7d39..d640425 100644 --- a/drivers/gpu/drm/i915/intel_panel.c +++ b/drivers/gpu/drm/i915/intel_panel.c @@ -311,9 +311,6 @@ void intel_panel_enable_backlight(struct drm_device *dev, if (dev_priv->backlight_level == 0) dev_priv->backlight_level = intel_panel_get_max_backlight(dev); - dev_priv->backlight_enabled = true; - intel_panel_actually_set_backlight(dev, dev_priv->backlight_level); - if (INTEL_INFO(dev)->gen >= 4) { uint32_t reg, tmp; @@ -326,7 +323,7 @@ void intel_panel_enable_backlight(struct drm_device *dev, * we don't track the backlight dpms state, hence check whether * we have to do anything first. */ if (tmp & BLM_PWM_ENABLE) - return; + goto set_level; if (dev_priv->num_pipe == 3) tmp &= ~BLM_PIPE_SELECT_IVB; @@ -347,6 +344,10 @@ void intel_panel_enable_backlight(struct drm_device *dev, I915_WRITE(BLC_PWM_PCH_CTL1, tmp); } } + +set_level: + dev_priv->backlight_enabled = true; + intel_panel_actually_set_backlight(dev, dev_priv->backlight_level); } static void intel_panel_init_backlight(struct drm_device *dev) -- 1.7.11.4
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