On Fri, 09 Jan 2015, Jeremiah Mahler <jmmahler@xxxxxxxxx> wrote: > Jani, all, > > On a Lenovo X1 Carbon if the display is off when suspend is entered > it will be off when it is resumed. A key must be pressed to restore > normal brightness. Please file a bug on [1] and attach dmesg with drm.debug=14 set, from boot to reproducing the problem. Thanks for the report. BR, Jani. [1] https://bugs.freedesktop.org/enter_bug.cgi?product=DRI&component=DRM/Intel > > xset dpms force off > sleep 1 > sudo systemctl suspend > (resume) > (screen off, press any key) > > The behavior I am accustomed to is for it to resume with the screen on. > All of my other machines behave this way and the X1 Carbon behaved this > way in the past. > > I performed a bisect and found that the following commit introduced the > problem. > > From 6dda730e55f412a6dfb181cae6784822ba463847 Mon Sep 17 00:00:00 2001 > From: Jani Nikula <jani.nikula@xxxxxxxxx> > Date: Tue, 24 Jun 2014 18:27:40 +0300 > Subject: [PATCH] drm/i915: respect the VBT minimum backlight brightness > > Historically we've exposed the full backlight PWM duty cycle range to > the userspace, in the name of "mechanism, not policy". However, it turns > out there are both panels and board designs where there is a minimum > duty cycle that is required for proper operation. The minimum duty cycle > is available in the VBT. > > The backlight class sysfs interface does not make any promises to the > userspace about the physical meaning of the range > 0..max_brightness. Specifically there is no guarantee that 0 means off; > indeed for acpi_backlight 0 usually is not off, but the minimum > acceptable value. > > Respect the minimum backlight, and expose the range acceptable to the > hardware as 0..max_brightness to the userspace via the backlight class > device; 0 means the minimum acceptable enabled value. To switch off the > backlight, the user must disable the encoder. > > As a side effect, make the backlight class device max brightness and > physical PWM modulation frequency (i.e. max duty cycle) > independent. This allows a follow-up patch to virtualize the max value > exposed to the userspace. > > Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx> > Reviewed-by: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx> > [danvet: s/BUG_ON/WARN_ON/] > Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx> > > -- > - Jeremiah Mahler -- Jani Nikula, Intel Open Source Technology Center _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
