Created attachment 25466 [details]
dmesg

Created attachment 25467 [details]
lspci

Created attachment 25468 [details]
Xorg.0.log

Created attachment 25469 [details]
dmi output of NV59

I am suffering the same problems on an Acer Aspire 5740-6491.  I reported the issue to acer-wmi, but it may not be a problem there.

kyle@noumena /sys/class/backlight/acpi_video0 $ cat brightness 
2
kyle@noumena /sys/class/backlight/acpi_video0 $ cat actual_brightness 
2
kyle@noumena /sys/class/backlight/acpi_video0 $ cat max_brightness 
9

Created attachment 25486 [details]
xrandr properties

Can modify the values of /sys/class/backlight/acpi_video0/brightness using xrandr, but it does not change the brightness of the screen.

please attach the output of "ls -l /sys/class/backlight/acpi_video0/"

Created attachment 25536 [details]
output of  /sys/class/backlight/acpi_video0/

and the output of "cat /sys/class/backlight/acpi_video0/device/path"

(In reply to comment #9)
> and the output of "cat /sys/class/backlight/acpi_video0/device/path"

[sachin@fedora-rawhide ~]$ sudo cat /sys/class/backlight/acpi_video0/device/path
\_SB_.PCI0.GFX0.DD02

okay, now we are sure this is a duplicate of bug #15528.

let's look at this issue in that bug report.

*** This bug has been marked as a duplicate of bug 15528 ***

Opening the bug since other bug fix didn't fixed my issue.

As Kyle in bug #15528 upgrade his BIOS before adding this boot option,
please upgrade your BIOS and see if it helps.

unfortunately there is no bios update for my laptop. Kyle's laptop was Acer but mine is Gateway

I have acer 5740 and suffering from the same problem; can't control brightness when running Linux.

(In reply to comment #15)
> I have acer 5740 and suffering from the same problem; can't control
> brightness
> when running Linux.

See this bug report. The discussion here solved the problem for my machine.

https://bugzilla.kernel.org/show_bug.cgi?id=15528

Thanks Kyle,

I have already tried that before posting here. I have compiled 2.6.34 kernel with the modification

`````````````````````
             DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
                     DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad T500"),
                },
        },
       
######## added part #############
        {
        .callback = dmi_enable_osi_linux,
        .ident = "Acer Aspire 5740",
        .matches = {
                     DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
                     DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5740"),
        },
       },
########### end ####################
     {}
};

```````````````````````

applied at  drivers/acpi/blacklist.c 

and also add acpi_osi="Linux" option at grub entry. But I can't control the brightness after the grub stage. If I completely disable the acpi; xwindow just hang the system ( driver intel) where vesa still works with a poor resolution and missing all the acpi features like battery monitor etc... Do I need to upgrade my BIOS or miss something else ?

Thanks Kyle,

I have already tried that before posting here. I have compiled 2.6.34 kernel with the modification

`````````````````````
             DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
                     DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad T500"),
                },
        },
       
######## added part #############
        {
        .callback = dmi_enable_osi_linux,
        .ident = "Acer Aspire 5740",
        .matches = {
                     DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
                     DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5740"),
        },
       },
########### end ####################
     {}
};

```````````````````````

applied at  drivers/acpi/blacklist.c 

and also add acpi_osi="Linux" option at grub entry. But I can't control the brightness after the grub stage. If I completely disable the acpi; xwindow just hang the system ( driver intel) where vesa still works with a poor resolution and missing all the acpi features like battery monitor etc... Do I need to upgrade my BIOS or miss something else ?

Oh! extremely sorry for the double post.

To: joydeep@infoservices.in

Yes, you need to upgrade your BIOS first.

Thanks Zhang :-)

I have upgraded the BIOS to 1.22 and the brightness control is working !! I have though noticed that startx every time starts the graphical mode with maximum  brightness. Is there any way to instruct startx or via xorg.conf to recognize already set brightness ?

with best wishes

I don't know.
The ACPI video driver set the backlight to the value when it's booted.
Maybe there are some user space apps. that change the backlight but that's beyond my scope.

No problem, at-least my brightness control is working fine. Thanks to all of you.

Created attachment 26896 [details]
custom DSDT

sachin,
please try the custom DSDT attached.

Unfortunately this does not work .. I have attached the dmesg log

Created attachment 26934 [details]
dmesg

Will you please try the following boot option and see whether it is helpful?
  > acpi_osi="!Linux" acpi_osi="!Windows 2006" acpi_osi="!Windows 2009"

Thanks

(In reply to comment #27)
> Will you please try the following boot option and see whether it is helpful?
>   > acpi_osi="!Linux" acpi_osi="!Windows 2006" acpi_osi="!Windows 2009"
> 
> Thanks

No it does not work.

Thanks

Same here, More over with those settings, brightness fn keys are not working any more.

Thanks

Joydeep, you don't need to try that.

Sachin, I give up my efforts on enabling the ACPI backlight control for this Gateway laptop as this really looks like a BIOS problem rather than Linux/ACPI bug.

I'll mark this bug as a duplicate of bug #14216. and let's see if there is any other way to control the backlight or not.

*** This bug has been marked as a duplicate of bug 14216 ***

I am sorry for reopening but I just came back from vacation.

I don't agree this is duplicate of bug 14216. Since the workaround given in the bug does not work in my case.

Also if this was a BIOS bug why backlight is working fine in Windows 7 ? Also if I pass "acpi=off" during the boot backlight works in Linux.

Thanks,
Sachin.

*** This bug has been marked as a duplicate of bug 19342 ***