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

karderio · n00b Joined: 17 Feb 2005 Posts: 8

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 !

karderio · n00b Joined: 17 Feb 2005 Posts: 8

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 · Posted: Sat Sep 03, 2011 10:03 am Post subject: GMA 4500M is a piece of s**t

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

karderio · n00b Joined: 17 Feb 2005 Posts: 8

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 · Posted: Tue Sep 20, 2011 5:07 am Post subject:

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

dennisn · Posted: Thu Sep 22, 2011 3:58 pm Post subject:

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 · Posted: Thu Sep 22, 2011 4:07 pm Post subject:

dennisn · Posted: Thu Sep 29, 2011 2:45 pm Post subject:

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!)