On November 18, 2016 6:42:40 AM GMT+01:00, "David C. Rankin" <drankinatty@suddenlinkmail.com> wrote:

On 11/17/2016 04:31 PM, David C. Rankin wrote:

...

All,

Laptop: HP 8760w, Quadro 3000M, nvidia-340xx packages.

The driver works perfectly (no errors in Xorg.0.log), but I have no way to control the screen brightness. I've followed the suggestions in:

https://wiki.archlinux.org/index.php/NVIDIA/Tips_and_tricks

but I still have no backlight control. Using the laptop function keys, the values in /sys/class/backlight/acpi_video0/brightness are properly set, e.g.

$ cat /sys/class/backlight/acpi_video0/brightness 8

(now tap the [func][F9], brightness lower, twice)

$ cat /sys/class/backlight/acpi_video0/brightness 6

(actual_brightness value tracks brightness)

$ cat /sys/class/backlight/acpi_video0/max_brightness 20

This works with OR without /etc/X11/xorg.conf.d/20-nvidia.conf:

Option "RegistryDwords" "EnableBrightnessControl=1"

Does anyone have any suggestions on anything else to try before I start loading the aur nvidia-bl or nvidiabl packages? I don't mind adding more software, but if there are a few more tweaks to try before going that route, I would like to try them first. Anybody get backlight working with a similar model laptop?

Let me add to this, that powerdevil is seeing the screen brightness changes and Udev is evidently applying them correctly. For example, pressing the function key to raise/lower brightness seems to generate the correct log entries:

Nov 17 23:36:37 seidr org_kde_powerdevil[710]: powerdevil: Screen brightness value: 6 Nov 17 23:36:37 seidr org_kde_powerdevil[710]: powerdevil: Screen brightness value max: 20 Nov 17 23:36:37 seidr dbus[334]: [system] Activating service name='org.kde.powerdevil.backlighthelper' (using servicehelper) Nov 17 23:36:37 seidr org_kde_powerdevil[710]: powerdevil: set screen brightness value: 7 Nov 17 23:36:37 seidr org_kde_powerdevil[710]: powerdevil: Screen brightness value max: 20 Nov 17 23:36:37 seidr dbus[334]: [system] Successfully activated service 'org.kde.powerdevil.backlighthelper' Nov 17 23:36:37 seidr org_kde_powerdevil[710]: powerdevil: Udev device changed "/sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/backlight/acpi_video0" "/sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/backlight/acpi_video0"

And, as noted above, the values in /sys/class/backlight/acpi_video0/brightness are changing as they should.

I'll give both the aur packages a try (I have both built -- but the nvidiabl package is currently disowwned and needs a maintainer if anyone is interested)

Do you use any special kernel boot parameters? Using "acpi_backlight=vendor" helped me in a similar situation, though it was about another option interfering with backlight control. Sylvain

On 11/18/2016 11:02 PM, David C. Rankin wrote:

I've got to get something figured out. This laptop will absolutely blind you when you open a browser, or anything with a white background. I have the backlight set at 40% in win10 and that works well. Here it looks like it is on MAX continually. I will keep at it. If anyone has any other idea, let me know. Thanks.

I don't believe this! I have I can effect the brightness with xrandr, but the output name is 'LVDS-0' instead of 'LVDS' (as it is on my other laptops). I don't know if this could be the whole problem with the normal backlight controls not working -- anyone have any idea? I'll just modify the xbacklight script to call xrandr instead of xbacklight and pass it fractional values between 0.5 and 1.0. Strange indeed. -- David C. Rankin, J.D.,P.E.

On Sat, 19 Nov 2016 02:00:11 -0600 "David C. Rankin" <drankinatty@suddenlinkmail.com> wrote:

[snip a whole bunch of maundering]

xrandr does not adjust the backlight. It adjusts the brightness, which while it may have the same visible effect may have negative effects on battery life and component wear compared to proper backlight adjustment. acpi_backlight=vendor is the default, acpi_backlight=none is invalid. The option you are looking for is acpi_backlight=video, which takes the backlight control away from the vendor driver and hands it back over to the standard ACPI backlight driver. This will generally solve the issue you are having. ~Celti

On 11/19/2016 03:09 AM, David C. Rankin wrote:

I'll go search to see if I can find the difference, but if you have a favorite link, I'd appreciate the help.

Got it. xrandr is software rendered darkening of pixel - no hardware control involved. Thanks. -- David C. Rankin, J.D.,P.E.

On 11/19/2016 03:38 AM, Christian Klaue wrote:

I am having exactly the same problem with my HP. I went as far as decompiling the ACPI bios. When I tried to compile it again, it threw a huge amount of errors. So I gave up. I didn't find any solution for my problem. I even tried other distros. I am still kind of convinced the error is in the ACPI module(s) of your UEFI. If you try to blame HP (as many people on their forum did before) they will ask you to test on Windows. Unfortunately there it works. The newest BIOS update doesn't fix the problem for my toy.

I am lucky to have an OLED. Please keep me updated if you find a solution.

Christian, You may be in luck. I did find a solution and now my backlight functions as it should using the nvidiabl kernel module (and a small helper script that I autostart in KDE, but you could just as easily start it in .xinitrc for any desktop) Basically, you have to use either of the following two packages to build a kernel module that will work with the proprietary nvidia driver: nvidia-bl https://aur.archlinux.org/packages/nvidia-bl/ nvidiabl https://aur.archlinux.org/packages/nvidiabl/ I built them both, but haven't tried nvidia-bl, (even though it was easier to build and should do the same thing) To build nvidiabl, just follow the notes on its aur page and it builds fine. nvidia-bl, builds without issue, just download the tarball, unpack it, and then a makepkg -s is all that is needed. Both provide the kernel module: /usr/lib/modules/extramodules-4.8-ARCH/nvidiabl.ko Just build, then 'modprobe nvidiabl', and you will have backlight control through: /sys/class/backlight/nvidia_backlight/brightness The kicker is that nothing talks to nvidia_backlight by default, instead all the normal backlight controls use: /sys/class/backlight/acpi_video0/brightness The way to get your controls to work is to watch the acpi_video0/brightness values and automatically set nvidia_backlight/brightness any time the earlier one changes value. This is where the helper script comes into play (actually 2 short scripts -- the second just to ease the sudo redirection issue) The first script just maps values (0-20) from acpi_video0/brightness into a range of (0-127) for nvidia_backlight/brightness (it calls the second script as a helper). Just launch the first script in whatever desktop you are using, and your backlight keys should work. If not, then you just have to copy whatever value you want for your backlight/brightness to nvidia_backlight/brightness, e.g. # echo 90 > /sys/class/backlight/nvidia_backlight/brightness Put both scripts in the same directory. You will need to configure sudo without a password for this to work when called as your normal user (as when using the laptop keys). The first is a quick modification of the xbacklight script. It reads the xbacklight value from acpi_video0 and then does a rough scale for what the nvidia_backlight value should be. Give it some name like nvbackligh.sh: #!/bin/sh path=/sys/class/backlight/acpi_video0 dest=/sys/class/backlight/nvidia_backlight dmax=$(<$dest/max_brightness) luminance() { read -r level < "$path"/actual_brightness factor=$((dmax / max)) nvbrt=$((level * factor)) case "$nvbrt" in [0-9] ) printf "%d" $nvbrt;; [0-9][0-9] ) printf "%d" $nvbrt;; [1][0-1][0-9] ) printf "%d" $nvbrt;; [1][2][0-9] ) printf "127";; default ) printf "error: in value conversion\n" exit 1;; esac } read -r max < "$path"/max_brightness inotifywait -me modify --format '' "$path"/actual_brightness | while read; do if [ $UID -eq 0 ]; then echo $(luminance) > "$dest"/brightness else sudo ./nvhelper.sh $(luminance) # helper script fi printf "luminance %s\n" "$(luminance)" done The second just echos the luminance value into nvidia_backlight/brightness which gets around sudo only applying to the echo and not the redirection. An alternative is calling it with 'su -c' (which you can configure pam to allow without a password if you are a member of the wheel group and you uncomment the first two lines in /etc/pam.d/su). The helper script nvhelper.sh is: #!/bin/sh [ $1 -lt 0 -o $1 -gt 127 ] && exit 1 ## check value out of range echo $1 > /sys/class/backlight/nvidia_backlight/brightness If you try the aur nvidia-bl package and it works. Let me know, it is a simpler package to build. I'll try and get time to try it over the next week or so. So now, after a couple of days relearning xrandr, backlight, the sysfs and what goes with what in the nvidia driver, that xrandr is a software pixel darkening scheme, we came to understand the kernel model approach is the correct approach for backlight control here...and it is working perfectly. (Now, if I could just get this damn HP laptop to boot grub without having to boot from USB and then boot grub on the hard drive, I'd be in great shape. Let me know if you have any questions. -- David C. Rankin, J.D.,P.E.

On Sun, 20 Nov 2016 10:56:16 +0100, Ralf Mardorf wrote:

On Sun, 20 Nov 2016 03:08:12 -0600, David C. Rankin wrote:

...

if [ $UID -eq 0 ]; then echo $(luminance) > "$dest"/brightness

Are you using the "helper script" because

sudo echo $(luminance) > "$dest"/brightness

doesn't work? If so, then consider to use

echo $(luminance) | sudo tee "$dest"/brightness

to get rid of the "helper script".

JFTR sudo sh -c would work, too, but IMO wouldn't make sense.

Well, this won't work for me. I don't have a NVidia. But I will search the web if there is a module for my Intel Skylake graphics. Although my brightness script actually works perfect. The only drawback currently: a few apps (e.g. chromium) reset the brightness to max upon their startup. Thanks anyway! Christian On Sun, 2016-11-20 at 03:08 -0600, David C. Rankin wrote:

On 11/19/2016 03:38 AM, Christian Klaue wrote:

...

I am having exactly the same problem with my HP. I went as far as decompiling the ACPI bios. When I tried to compile it again, it threw a huge amount of errors. So I gave up. I didn't find any solution for my problem. I even tried other distros. I am still kind of convinced the error is in the ACPI module(s) of your UEFI. If you try to blame HP (as many people on their forum did before) they will ask you to test on Windows. Unfortunately there it works. The newest BIOS update doesn't fix the problem for my toy.

I am lucky to have an OLED. Please keep me updated if you find a solution.

Christian,

  You may be in luck. I did find a solution and now my backlight functions as it should using the nvidiabl kernel module (and a small helper script that I autostart in KDE, but you could just as easily start it in .xinitrc for any desktop) Basically, you have to use either of the following two packages to build a kernel module that will work with the proprietary nvidia driver:

nvidia-bl https://aur.archlinux.org/packages/nvidia-bl/

nvidiabl https://aur.archlinux.org/packages/nvidiabl/

  I built them both, but haven't tried nvidia-bl, (even though it was easier to build and should do the same thing)

  To build nvidiabl, just follow the notes on its aur page and it builds fine. nvidia-bl, builds without issue, just download the tarball, unpack it, and then a makepkg -s is all that is needed.

  Both provide the kernel module:

/usr/lib/modules/extramodules-4.8-ARCH/nvidiabl.ko

  Just build, then 'modprobe nvidiabl', and you will have backlight control through:

/sys/class/backlight/nvidia_backlight/brightness

  The kicker is that nothing talks to nvidia_backlight by default, instead all the normal backlight controls use:

/sys/class/backlight/acpi_video0/brightness

  The way to get your controls to work is to watch the acpi_video0/brightness values and automatically set nvidia_backlight/brightness any time the earlier one changes value. This is where the helper script comes into play (actually 2 short scripts -- the second just to ease the sudo redirection issue)

  The first script just maps values (0-20) from acpi_video0/brightness into a range of (0-127) for nvidia_backlight/brightness (it calls the second script as a helper). Just launch the first script in whatever desktop you are using, and your backlight keys should work. If not, then you just have to copy whatever value you want for your backlight/brightness to nvidia_backlight/brightness, e.g.

 # echo 90 > /sys/class/backlight/nvidia_backlight/brightness

  Put both scripts in the same directory. You will need to configure sudo without a password for this to work when called as your normal user (as when using the laptop keys). The first is a quick modification of the xbacklight script. It reads the xbacklight value from acpi_video0 and then does a rough scale for what the nvidia_backlight value should be. Give it some name like nvbackligh.sh:

#!/bin/sh

path=/sys/class/backlight/acpi_video0 dest=/sys/class/backlight/nvidia_backlight dmax=$(<$dest/max_brightness)

luminance() {     read -r level < "$path"/actual_brightness     factor=$((dmax / max))     nvbrt=$((level * factor))     case "$nvbrt" in         [0-9]       )  printf "%d" $nvbrt;;         [0-9][0-9]  )  printf "%d" $nvbrt;;         [1][0-1][0-9] )  printf "%d" $nvbrt;;         [1][2][0-9] )  printf "127";;         default     )  printf "error: in value conversion\n"                        exit 1;;     esac }

read -r max < "$path"/max_brightness

inotifywait -me modify --format '' "$path"/actual_brightness | while read; do     if [ $UID -eq 0 ]; then         echo $(luminance) > "$dest"/brightness     else         sudo ./nvhelper.sh $(luminance)  # helper script     fi     printf "luminance %s\n" "$(luminance)" done

  The second just echos the luminance value into nvidia_backlight/brightness  which gets around sudo only applying to the echo and not the redirection. An alternative is calling it with 'su -c' (which you can configure pam to allow without a password if you are a member of the wheel group and you uncomment the first two lines in /etc/pam.d/su). The helper script nvhelper.sh is:

#!/bin/sh [ $1 -lt 0 -o $1 -gt 127 ] && exit 1  ## check value out of range echo $1 > /sys/class/backlight/nvidia_backlight/brightness

  If you try the aur nvidia-bl package and it works. Let me know, it is a simpler package to build. I'll try and get time to try it over the next week or so.

  So now, after a couple of days relearning xrandr, backlight, the sysfs and what goes with what in the nvidia driver, that xrandr is a software pixel darkening scheme, we came to understand the kernel model approach is the correct approach for backlight control here...and it is working perfectly.

(Now, if I could just get this damn HP laptop to boot grub without having to boot from USB and then boot grub on the hard drive, I'd be in great shape. Let me know if you have any questions.