Created attachment 139641 [details] kern.log drm.debug=0xe with v3.14-890-gc675949 Hi there, Sorry Jani, I'm afraid this one is for you too. This is the bug I experienced while testing the kernel from the drm-intel repo for bug 75791, and it is confirmed in v3.15 on the same machine. Symptoms: - backlight level stays at maximum - empty /sys/class/backlight - this might be unrelated, but X (KDM) almost always initially starts to a black screen, and I have to switch to a VT and back to the X VT to restore the display; more rarely it's the other way round: KDM starts normally but when I switch to a VT it is a black screen Bisect result: commit c675949ec58ca50d5a3ae3c757892f1560f6e896 Author: Jani Nikula <jani.nikula@intel.com> Date: Wed Apr 9 11:31:37 2014 +0300 drm/i915: do not setup backlight if not available according to VBT The kern.log attached was obtained with this commit and drm.debug=0xe; you can see the message "native backlight control not available per VBT" introduced by this commit appear.
Aww crap. Please attach /sys/kernel/debug/dri/0/i915_opregion.
Same bisect result but likely different fix required: https://bugs.freedesktop.org/show_bug.cgi?id=79813
BTW do you have CONFIG_BACKLIGHT_APPLE=y? Have you tried the module?
(In reply to Jani Nikula from comment #1) > Aww crap. Please attach /sys/kernel/debug/dri/0/i915_opregion. You already know it's empty, that didn't change, sorry ;-) (In reply to Jani Nikula from comment #3) > BTW do you have CONFIG_BACKLIGHT_APPLE=y? Have you tried the module? I have CONFIG_BACKLIGHT_APPLE=m, the module apple_bl is loaded and I have a directory "/sys/bus/acpi/drivers/Apple backlight", but I don't know what to do with it.
(In reply to Matteo Cypriani from comment #4) > (In reply to Jani Nikula from comment #1) > > Aww crap. Please attach /sys/kernel/debug/dri/0/i915_opregion. > > You already know it's empty, that didn't change, sorry ;-) > > > (In reply to Jani Nikula from comment #3) > > BTW do you have CONFIG_BACKLIGHT_APPLE=y? Have you tried the module? > > I have CONFIG_BACKLIGHT_APPLE=m, the module apple_bl is loaded and I have a > directory "/sys/bus/acpi/drivers/Apple backlight", but I don't know what to > do with it. Do you have it in /sys/class/backlight? Do you have CONFIG_BACKLIGHT_CLASS_DEVICE=y?
Please attach the dump produced by intel_bios_dumper tool from the intel-gpu-tools package: http://cgit.freedesktop.org/xorg/app/intel-gpu-tools/
(In reply to Jani Nikula from comment #5) > Do you have it in /sys/class/backlight? I don't understand, do I have what? Anyway, /sys/class/backlight is empty, so I guess the answer is no. > Do you have > CONFIG_BACKLIGHT_CLASS_DEVICE=y? I do. (In reply to Jani Nikula from comment #6) > Please attach the dump produced by intel_bios_dumper tool When I run it (as root), I get this error message: "Couldn't read graphics card ROM: Input/output error" Strace exerpt: open("/sys/bus/pci/devices/0000:00:02.0/rom", O_RDWR|O_CLOEXEC) = 4 fstat(4, {st_mode=S_IFREG|0600, st_size=131072, ...}) = 0 write(4, "1", 1) = 1 lseek(4, 0, SEEK_SET) = 0 read(4, 0x2426f60, 131072) = -1 EIO (Input/output error) lseek(4, 0, SEEK_SET) = 0 write(4, "0", 1) = 1 close(4) = 0 And indeed: # ls -l /sys/bus/pci/devices/0000:00:02.0/rom -rw------- 1 root root 131072 Jun 16 10:54 /sys/bus/pci/devices/0000:00:02.0/rom # hexdump /sys/bus/pci/devices/0000:00:02.0/rom hexdump: /sys/bus/pci/devices/0000:00:02.0/rom: Input/output error # cp /sys/bus/pci/devices/0000:00:02.0/rom /tmp cp: error reading '/sys/bus/pci/devices/0000:00:02.0/rom': Input/output error cp: failed to extend '/tmp/rom': Input/output error zsh: exit 1 cp /sys/bus/pci/devices/0000:00:02.0/rom /tmp Ay idea how to solve this?
(In reply to Matteo Cypriani from comment #7) > (In reply to Jani Nikula from comment #5) > > Do you have it in /sys/class/backlight? > > I don't understand, do I have what? Anyway, /sys/class/backlight is empty, > so I guess the answer is no. Weird, apple_bl should add apple_backlight interface there.
I don't think I've seen this before. Jun 13 09:17:38 vt kernel: [ 34.282877] [drm:intel_opregion_setup] graphic opregion physical addr: 0x0 Jun 13 09:17:38 vt kernel: [ 34.282879] [drm:intel_opregion_setup] ACPI OpRegion not supported! Jun 13 09:17:38 vt kernel: [ 34.282945] i915 0000:00:02.0: Invalid ROM contents Jun 13 09:17:38 vt kernel: [ 34.282947] [drm:intel_parse_bios] VBT signature missing Jun 13 09:17:38 vt kernel: [ 34.282948] [drm] failed to find VBIOS tables
Created attachment 140081 [details] drm/i915: default to having backlight if VBT not available Matteo, please try this patch on top of 3.15 or later.
It works. With that patch applied on top of v3.15 I'm back to the behaviour of v3.14, and after applying the patch that solved bug 75791 I'm back to the everything-works-fine state of v3.13. Thanks for your work and your reactiveness!
commit 56c4b63aaf4c2cd91966b2a5e69e5367bea60bbe Author: Jani Nikula <jani.nikula@intel.com> Date: Tue Jun 17 15:47:05 2014 +0300 drm/i915: default to having backlight if VBT not available Thanks for the report and testing.