Laptop is HP dm3t with nvidia g105m graphics. Problem: I have no devices in /proc/acpi/video or /sys/class/backlight with which to control the screen's brightness. Both Fn+Keys (F1 and F2) have no keycodes/scancodes. Brightness cannot be adjusted. I believe this is an acpi problem which is why I'm filing it here. Please forgive my mistake if any as I'm not quite sure what I'm doing here.
Created attachment 23885 [details] dmesg
Created attachment 23886 [details] lspci
Created attachment 23887 [details] acpidump
Created attachment 23888 [details] dsdt
Created attachment 23889 [details] dmidecode
Hi, Geoff From the acpidump in comment #3 it seems that there exists the _BCL/_BCM object, which is required by ACPI backlight interface. Will you please try to enable "CONFIG_ACPI_VIDEO" in kernel configuration and see whether there exists the acpi backlight interface under /sys/class/backlight/? If it exists, please check whether the backlight can be adjusted by using /sys/class/backlight/acpi_video0/brightness. Thanks.
zgrep CONFIG_ACPI_VIDEO /proc/config.gz CONFIG_ACPI_VIDEO=m I will try to compile a new kernel with CONFIG_ACPI_VIDEO=y and get back to you.
there are two problem here: No.1. the backlight control problem I checked the DSDT and it seems that there are Backlight control methods for device 00:01.0 and 00:02.0. but 1. _DOS is missed for pci 00:01.0 device 2. there is no pci 00:02.0 device This explains why /proc/acpi/video/ is NULL. But anyway, I don't think this is an ACPI problem. that's because you're using nvidia graphics on this laptop, which means that ACPI table doesn't have the backlight control methods for this device, i.e. backlight can not be controlled via ACPI. IMO, this is a nvidia graphics problem. No.2. the hotkey problem could you please attach the output of "grep . /sys/firmware/acpi/interrupts/*" both before and after pressing the hotkey?
Created attachment 23901 [details] Before F1/F2
Created attachment 23902 [details] After F1
Created attachment 23903 [details] After F2
So if I tried to use the "nv" driver instead of "nvidia" then it should theoretically work if this is indeed an nvidia driver issue? I will test and report.
The "nv" driver apparently does not support my GPU. Zhang, I will have to respectfully disagree with you about it being an nvidia driver problem anyway, I've spoken to someone on nvnews.net forum with the same GPU using linux and that person reports that brightness can be adjusted on his machine. That to me indicates something having to do with my machine's ACPI or BIOS rather than the graphics card.
OK @ykzhao: I've compiled a custom kernel with CONFIG_ACPI_VIDEO=y, no device is created in /proc/acpi or in /sys/class/ and the hotkeys still do nothing. @Zhang: I've updated to the latest beta of the nvidia binary driver 194.42 => 195.22-3... I still cannot adjust the brightness by any method. Guys status is "Need Info" what else do you need?
Created attachment 24110 [details] custom DSDT please try this DSDT. there should be an ACPI video device after applying this custom DSDT but I'm not sure if it can work for you.
(In reply to comment #13) > The "nv" driver apparently does not support my GPU. > > Zhang, I will have to respectfully disagree with you about it being an nvidia > driver problem anyway, I've spoken to someone on nvnews.net forum with the > same > GPU using linux and that person reports that brightness can be adjusted on > his > machine. How does he control the backlight? I just want to say that the backlight can not be controlled via ACPI because ACPI just offers the backlight control methods for the integrated graphics card, which is not available on your laptop. but anyway it works occasionally, so you can still try the custom DSDT in comment #15. Native graphics driver controls the backlight in some cases, especially for the nvidia graphics cards. If the custom DSDT in comment #15 doesn't work for you, I suggest you to open a bug at bugs.freedesktop.org to see if the nvidia experts there can help. Because there is little that we ACPI guys can help here. :( BTW: I remember that there was once a tool named smartdimmer which can be used for brightness switching for nvidia graphics.
This link has a user with a different laptop, but same video card using Ubuntu 32-bit 9.10. He doesn't have devices in /sys/class/backlight or /proc/acpi/ either. HOWEVER, he is able to change his brightness level with smartdimmer. I am not able, smartdimmer returns an error about my card being unsupported and not being able to shadow the video BIOS. https://bugs.launchpad.net/ubuntu/+source/hal/+bug/477429 I still haven't tried the DSDT, I'll get back to you when I do. Actually, I'm very confused now as to what exactly the problem is...
(In reply to comment #17) > Actually, I'm very confused now as to what exactly the problem is... okay, let me state the problem in this way, 1. ACPI can control backlight, but it depends on the BIOS. And unfortunately, we don't find any ACPI backlight support for nvidia graphics card in this BIOS. 2. Native driver can always control the backlight! Intel graphics driver takes over the backlight switching only if ACPI backlight control is not available, via xrandr tool. And nvidia graphics has its own way to control the backligth, e.g. smartdimmer for some laptops and maybe some other tool for some other nvidia laptops, but we ACPI people don't know. This is beyond ACPI's scope. :( that's why I suggest you to open a bug at bugs.freedesktop.org, nvidia graphics guys there may help you. > This link has a user with a different laptop, but same video card using > Ubuntu > 32-bit 9.10. He doesn't have devices in /sys/class/backlight or /proc/acpi/ > either. HOWEVER, he is able to change his brightness level with smartdimmer. > I am not able, smartdimmer returns an error about my card being unsupported > and > not being able to shadow the video BIOS. > okay, here is an example, I don't know what this means, but the nvidia graphics guys may know what's happening on this laptop and offer you some help. :) Well, I have to close this bug because BIOS doesn't provide aby ACPI backlight control interface. please re-open it if you still have any questions.