[Bugme-new] [Bug 41042] New: Changing the backlight brightness may freeze the laptop

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=41042

           Summary: Changing the backlight brightness may freeze the
                    laptop
           Product: ACPI
           Version: 2.5
    Kernel Version: 3.0.0
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: Other
        AssignedTo: acpi_other at kernel-bugs.osdl.org
        ReportedBy: joalonsof at gmail.com
        Regression: No


Created an attachment (id=68732)
 --> (https://bugzilla.kernel.org/attachment.cgi?id=68732)
acpidump

Sometimes when pressing the keys to adjust screen brightness, the laptop
freezes.

The script below reproduces the freeze:

for (( i=1 ; i <= 100 ; i++))
do
    echo 3 >/sys/class/backlight/acpi_video0/brightness
done

The screen shows the last image, no disk/net/keyboard activity, and the
processor cooler increases the air flow indicating a heavy usage of CPU
(interrupt ??, spinlock ??)

I tested with kernel version 3.0.0, 2.6.38 and fedora 15 kernels.

laptop: Dell Inspiron, i5, intel graphics

follow acpidump and lspci -vxxx

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