# Blank screen with GMA 4500M on Acer 5736z (backlight off)

## karderio

I just installed gentoo, from the minimal cd, on my new laptop : Acer Aspire 5736z. I compiled a kernel from gentoo-sources, using the i915 drivers with KMS (for the intel 4500M card the laptop has). On the first boot the screen was blank, the issue being that the backlight was off. I could barely read the screen with a flashlight.The screen blanks just after the kernel loads, I don't even get a text terminal.

I found quite a few people with the same issue, but few solutions apart from a workaroud here : https://bugs.launchpad.net/ubuntu/+source/linux/+bug/752165 . So, running 'setpci -s 00:02.0 F4.B=00' as root switched the backlight on again and I made a script to run this at boot, but it seems that the issue repeats after the machine goes to sleep or after changing resolution. If you are interested in the workaroud I put instructions on gentoo-wiki : http://en.gentoo-wiki.com/wiki/Intel_GMA#Backlight_off_at_boot_on_4500M . Although the screen now displays, I cannot ajust the brightness.

By disabling KMS (but then X can't use the intel driver), or using another driver the issue goes away. I tried 3.0.3 kernel, same issue. I would guess this is a kernel bug with i915 KMS and GMA 4500M, as suggested in the ubuntu bug (above link). Booting with "nomodeset" on the Grub command line gets you a low resolution terminal, but no intel driver for X.

There seems to be a bug report for this for the kernel : https://bugzilla.kernel.org/show_bug.cgi?id=35072 , but after more than three months there is no response from any devs. I'm wondering if this should be reported to bugs.freedesktop.org ; I found no bug concerning this there and the intel driver website this as the place to report issues.

I tried the latest versions of Ubuntu and Mint on a livecd, same blank screen. Mint-Debian works.

Would be great if the backlight would just work, but to be able to dim it is essential to me, any ideas ? Thanks !

```
emerge --info

Portage 2.1.10.3 (default/linux/amd64/10.0/desktop/gnome, gcc-4.4.5, glibc-2.12.2-r0, 2.6.39-gentoo-r3 x86_64)

=================================================================

System uname: Linux-2.6.39-gentoo-r3-x86_64-Pentium-R-_Dual-Core_CPU_T4500_@_2.30GHz-with-gentoo-2.0.3

Timestamp of tree: Thu, 25 Aug 2011 10:30:01 +0000

distcc 3.1 x86_64-pc-linux-gnu [enabled]

ccache version 2.4 [enabled]

app-shells/bash:          4.1_p9

dev-lang/python:          2.7.1-r1, 3.1.3-r1

dev-util/ccache:          2.4-r9

dev-util/cmake:           2.8.4-r1

dev-util/pkgconfig:       0.26

sys-apps/baselayout:      2.0.3

sys-apps/openrc:          0.8.3-r1

sys-apps/sandbox:         2.4

sys-devel/autoconf:       2.13, 2.68

sys-devel/automake:       1.11.1

sys-devel/binutils:       2.21.1

sys-devel/gcc:            4.4.5

sys-devel/gcc-config:     1.4.1-r1

sys-devel/libtool:        2.4-r1

sys-devel/make:           3.82

sys-kernel/linux-headers: 2.6.36.1 (virtual/os-headers)

sys-libs/glibc:           2.12.2

Repositories: gentoo

ACCEPT_KEYWORDS="amd64"

ACCEPT_LICENSE="* -@EULA"

CBUILD="x86_64-pc-linux-gnu"

CFLAGS="-O2 -march=core2 -pipe -fomit-frame-pointer"

CHOST="x86_64-pc-linux-gnu"

CONFIG_PROTECT="/etc"

CONFIG_PROTECT_MASK="/etc/ca-certificates.conf /etc/env.d /etc/fonts/fonts.conf /etc/gconf /etc/gentoo-release /etc/sandbox.d /etc/terminfo"

CXXFLAGS="-O2 -march=core2 -pipe -fomit-frame-pointer"

DISTDIR="/usr/portage/distfiles"

FEATURES="assume-digests binpkg-logs ccache distcc distlocks ebuild-locks fixlafiles fixpackages news parallel-fetch protect-owned sandbox sfperms strict unknown-features-warn unmerge-logs unmerge-orphans userfetch"

FFLAGS=""

GENTOO_MIRRORS="http://mirrors.linuxant.fr/distfiles.gentoo.org/ http://gentoo.modulix.net/gentoo/ http://mirror.qubenet.net/mirror/gentoo/"

LANG="en_US.UTF-8"

LDFLAGS="-Wl,-O1 -Wl,--as-needed"

LINGUAS="en fr"

MAKEOPTS="-j5"

PKGDIR="/usr/portage/packages"

PORTAGE_CONFIGROOT="/"

PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --compress --force --whole-file --delete --stats --timeout=180 --exclude=/distfiles --exclude=/local --exclude=/packages"

PORTAGE_TMPDIR="/var/tmp"

PORTDIR="/usr/portage"

PORTDIR_OVERLAY=""

SYNC="rsync://rsync.gentoo.org/gentoo-portage"

USE="X a52 aac acpi alsa amd64 amr apng avi bamr berkdb branding bzip2 cairo cdda cddb cdparanoia cdr cleartype cli consolekit cracklib crypt css cups curl cxx dbus device-mapper dirac disk-partition divx dri dts dvb dvd dvdr emboss encode exif extras faac faad fam ffmpeg firefox flac fontconfig fortran gdbm gdu gif glibc-omitfp gmail gnome gnome-keyring gphoto2 gpm gstreamer gtk hunspell iconv icu ipod ipv6 jabbereg jadetex jbig jpeg jpeg2k kdrive lame lcdfilter lcms libnotify libv4l2 lpng12 mad matroska mms mmx mng modules mp mp3 mp4 mpeg mtp mudflap multilib musepack musicbrainz nautilus ncurses nls nptl nptlonly ntfs offensive ogg opencore-amr opengl openmp pam pango pcre pdf png policykit posix ppds pppd python qt3support quicktime raw readline rtmp scanner schroedinger session shorten sockets speex spell sse sse2 sse3 ssl ssse3 startup-notification stream svg synaptics sysfs tcpd theora threads tiff trayicon truetype udev unicode usb v4l2 vaapi vorbis vpx wavpack win wireless wma x x264 xcb xcomposite xml xnest xorg xulrunner xv xvid zlib" ALSA_CARDS="ali5451 als4000 atiixp atiixp-modem bt87x ca0106 cmipci emu10k1x ens1370 ens1371 es1938 es1968 fm801 hda-intel intel8x0 intel8x0m maestro3 trident usb-audio via82xx via82xx-modem ymfpci" ALSA_PCM_PLUGINS="adpcm alaw asym copy dmix dshare dsnoop empty extplug file hooks iec958 ioplug ladspa lfloat linear meter mmap_emul mulaw multi null plug rate route share shm softvol" APACHE2_MODULES="actions alias auth_basic authn_alias authn_anon authn_dbm authn_default authn_file authz_dbm authz_default authz_groupfile authz_host authz_owner authz_user autoindex cache cgi cgid dav dav_fs dav_lock deflate dir disk_cache env expires ext_filter file_cache filter headers include info log_config logio mem_cache mime mime_magic negotiation rewrite setenvif speling status unique_id userdir usertrack vhost_alias" CALLIGRA_FEATURES="kexi words flow plan stage tables krita karbon braindump" CAMERAS="ptp2" COLLECTD_PLUGINS="df interface irq load memory rrdtool swap syslog" ELIBC="glibc" GPSD_PROTOCOLS="ashtech aivdm earthmate evermore fv18 garmin garmintxt gpsclock itrax mtk3301 nmea ntrip navcom oceanserver oldstyle oncore rtcm104v2 rtcm104v3 sirf superstar2 timing tsip tripmate tnt ubx" INPUT_DEVICES="evdev keyboard mouse synaptics" KERNEL="linux" LCD_DEVICES="bayrad cfontz cfontz633 glk hd44780 lb216 lcdm001 mtxorb ncurses text" LINGUAS="en fr" PHP_TARGETS="php5-3" RUBY_TARGETS="ruby18" USERLAND="GNU" VIDEO_CARDS="intel" XTABLES_ADDONS="quota2 psd pknock lscan length2 ipv4options ipset ipp2p iface geoip fuzzy condition tee tarpit sysrq steal rawnat logmark ipmark dhcpmac delude chaos account" 

Unset:  CPPFLAGS, CTARGET, EMERGE_DEFAULT_OPTS, INSTALL_MASK, LC_ALL, PORTAGE_BUNZIP2_COMMAND, PORTAGE_COMPRESS, PORTAGE_COMPRESS_FLAGS, PORTAGE_RSYNC_EXTRA_OPTS

```

```
lspci

00:00.0 Host bridge: Intel Corporation Mobile 4 Series Chipset Memory Controller Hub (rev 07)

00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07)

00:02.1 Display controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07)

00:1a.0 USB Controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #4 (rev 03)

00:1a.1 USB Controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #5 (rev 03)

00:1a.7 USB Controller: Intel Corporation 82801I (ICH9 Family) USB2 EHCI Controller #2 (rev 03)

00:1b.0 Audio device: Intel Corporation 82801I (ICH9 Family) HD Audio Controller (rev 03)

00:1c.0 PCI bridge: Intel Corporation 82801I (ICH9 Family) PCI Express Port 1 (rev 03)

00:1c.1 PCI bridge: Intel Corporation 82801I (ICH9 Family) PCI Express Port 2 (rev 03)

00:1c.2 PCI bridge: Intel Corporation 82801I (ICH9 Family) PCI Express Port 3 (rev 03)

00:1d.0 USB Controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #1 (rev 03)

00:1d.1 USB Controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #2 (rev 03)

00:1d.2 USB Controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #3 (rev 03)

00:1d.3 USB Controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #6 (rev 03)

00:1d.7 USB Controller: Intel Corporation 82801I (ICH9 Family) USB2 EHCI Controller #1 (rev 03)

00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev 93)

00:1f.0 ISA bridge: Intel Corporation ICH9M LPC Interface Controller (rev 03)

00:1f.2 SATA controller: Intel Corporation ICH9M/M-E SATA AHCI Controller (rev 03)

00:1f.3 SMBus: Intel Corporation 82801I (ICH9 Family) SMBus Controller (rev 03)

04:00.0 Network controller: Atheros Communications Inc. AR9287 Wireless Network Adapter (rev 01)

05:00.0 Ethernet controller: Broadcom Corporation NetLink BCM57780 Gigabit Ethernet PCIe (rev 01)

```

Last edited by karderio on Sat Aug 27, 2011 3:04 pm; edited 1 time in total

----------

## karderio

Hum, either I'm not paying attention to what I'm doing, or the forum showed me a preview of my very long post ok but them truncated it. I've edited the post to provide the kernel config speratly (here in fact :).

Is there a better way to provide such verbose information in posts ? I checked and saw others providing raw kernel configs here, so I copied. I avoided pastebin intentionnaly.

EDIT: Well, I thought it was probably me not paying attention, but the forum shows a complete and correct preview of my long kernel conf post, but truncates it upon submission, without warning.  Kernel config here : http://pastebin.com/ViRaaESF

----------

## smartass

I also have this GMA on my Acer Extensa 5635Z

So here are my experiences that I'd like to share with you or anyone else:

 in my BIOS, I can select the memory allocated for the card, by default it's set to 64 MB, can be set to max 128MB on my model.

 I've had success with using the acpi_osi kernel parameter

I recommend playing with it through the interactive grub editing boot menu, when you find smth that works add it to menu.lst or grub.conf

acpi_osi= without setting it to anything like this, I can adjust the brightness via keyboard keys through some hardware-only interface, which means that xbacklight and any DE utility won't be able to change the brightness and the interface in /sys/ also won't work, but on the other hand, you can directly change brightness even on a tty with the keyboard keys

acpi_osi=Linux enables some ACPI software-only interface, so you must use some program like xbacklight or a DE utility or write to the /sys/ interface. Using xbindkeys to bind XF86BacklightLower or smth (check with xev what your keyboard keys trigger)  to a script to write to the /sys/ interface or xbacklight works well

Hope this helps, good luck  :Smile: 

----------

## karderio

Thank you, that is much better !

I added "acpi_osi=Linux" to my kernel boot line. Now I can adjust the brightness with the keyboard.

The screen boots to a blank screen by default however, so I have to press the key to turn the backlight on after booting.

The gnome-power-manager based brightness control applet does not work either.

I have filed a bug here : https://bugs.freedesktop.org/show_bug.cgi?id=40455

----------

## cach0rr0

i have an acer aspire 4736z, which has that same Intel GM4500 (using i915), and I've had the dodgy backlight issues for some time myself. 

For me, this manifests itself more often than not when ive been playing with rebooting the machine without the AC adapter plugged in. Haven't been able to pinpoint it. But what actually happens is a completely black screen. I know it boots, because CTRL+ALT+DELETE or Alt+SysRq+B reboot the machine. 

I then have to append 'i915.modeset=0' to the kernel command line, boot without KMS, login, and

```

echo 8 > /sys/class/backlight/acpi_video0/brightness

```

at which point if I reboot, KMS is fine (until it happens the next time of course)

The other thing I can do, is just fly completely blind, logging in and typing all of that whilst i have a completely black screen, using the HDD activity light to determine how far along i am in the boot process. If I do this, then reboot, all is fine. 

I've resigned myself to the fact that this is some kernel DRM bug that'll ultimately be fixed, and I'm not going to stress out because it's a bug that's been around for roughly a year now  :Laughing: 

EDIT:

actually, since i already run a custom initramfs for crypto stuff, i wonder if i could just add in one quick line to adjust that /sys value as part of /init

i doubt it, though. If that were an immediate setting, it would take effect when I did it using the "flying blind" method described above.

----------

## dennisn

The problem is less serious with my Intel GMA3150 -- with KMS, I get a few (5-10?) seconds of a completely blank/disabled screen, then it suddently turns on, with my login prompt -- but I miss all the boot messages. None of the numerous workarounds floating around on the net so far have any effect.

I'm convinced it's something with the kernel (currently 3.0.4). If I interrupt openrc's boot sequence ('I'), and do nothing, it still goes blank, and then turns on after a few seconds -- some kind of latent kernel activity.

----------

## cach0rr0

 *dennisn wrote:*   

> 
> 
> I'm convinced it's something with the kernel (currently 3.0.4). If I interrupt openrc's boot sequence ('I'), and do nothing, it still goes blank, and then turns on after a few seconds -- some kind of latent kernel activity.

 

oh, it's definitely an issue with the kernel. It's just a matter of tracking down which obscenely specific issue you have. 

There seem to be a gazillion GM45 cards out there, for example, each with their own specific DRM bugs that cause this issue, and where you may see one i915 fix for one specific card, ten others have no fix.

----------

## dennisn

On my GMA3150, the VGA output works nicely on boot (no blanking throughout the boot process). Only the LVDS seems to be affected, for a few seconds. (Still very annoying!)

----------

