Re: PROBLEM: Acer D255E Backlight out for 10 seconds with ACPI

[joeyli <jlee@suse.com>]

於 三，2012-10-03 於 08:26 -0400，Dan 提到：
> >> Acpidump is attached.
> >>
> >
> > I traced your DSDT at this morning, didn't see problem in _BCL, _BCM
> and
> > _BQC.
> > Per DSDT, the _BQC on this machine used brightness value but not
> index,
> > so 'video.use_bios_initial_backlight=0' should works to you for set
> the
> > backlight to max_level when acpi/video driver loaded.
> >
> > And, the value of max_level in package of _BCL is 100, there have no
> 0
> > value in level list:
> >
> >     Method (_BCL, 0, NotSerialized)
> >     {
> >         Return (Package (0x0C)
> >         {
> >             0x46,               /* level on AC */
> >             0x28,               /* level on Battery */
> >             0x0A,               /* 10 */
> >             0x14,               /* 20 */
> >             0x1E,
> >             0x28,
> >             0x32,
> >             0x3C,
> >             0x46,
> >             0x50,
> >             0x5A,
> >             0x64                /* 100 */
> >
> > That strange for 'video.use_bios_initial_backlight=0' doesn't work
> to
> > you for set the backlight level to maximum.
> > Could you please share the acpi debug log? Please add the following
> > kernel parameter when system boot. Please also check the kernel
> config
> > need CONFIG_ACPI_DEBUG=y:
> >
> >         acpi.debug_level=0x0000000F acpi.debug_layer=0xffffffff
> log_buf_len=5M
> >
> > Please attached on your dmesg or boot message after system boot
> finished. Hope we
> > can find any hint from acpi debug log.
> >
> >
> > Thanks a lot!
> > Joey Lee
> >
> 
> I've attached the resulting dmesg log. I also set the loglevel to 8
> during this so I could watch the messages on the console. The last
> message I could see before the backlight went out was at 5.93 seconds.
> I tried looking through the log around there, but it's over my head.
> 
> Thank you,
> Dan
> 

Thanks for your acpi debug log.

Per acpi debug log, the DD02 device have backlight control capability.
The default brightness value is 30, acpi/video driver set brightness
value to 100 then set it back to 30 for determine does _BQC use index
but not brightness level:

[    3.113825] ACPI: Execute Method [\_SB_.PCI0.OVGA.DD02._BCL] (Node ffff88007b741c58)
[    3.115980] ACPI: Execute Method [\_SB_.PCI0.OVGA.DD02._BQC] (Node ffff88007b741ca8)
[    3.118310] exregion-0302 [00] ex_system_io_space_han: System-IO (width 32) R/W 1 Address=0000000000000080
[    3.220145]    utils-0286 [00] evaluate_integer      : Return value [30]				<=== default brightness value is 30(default value set by BIOS)
[    3.222315] ACPI: Execute Method [\_SB_.PCI0.OVGA.DD02._BCM] (Node ffff88007b741c80)
[    3.225422] exregion-0302 [00] ex_system_io_space_han: System-IO (width 8) R/W 1 Address=0000000000000072
[    3.227947] exregion-0302 [00] ex_system_io_space_han: System-IO (width 8) R/W 1 Address=0000000000000073
[    3.230424] ACPI: Execute Method [\_SB_.PCI0.OVGA.DD02._BQC] (Node ffff88007b741ca8)
[    3.233123] exregion-0302 [00] ex_system_io_space_han: System-IO (width 32) R/W 1 Address=0000000000000080
[    3.333487]    utils-0286 [00] evaluate_integer      : Return value [100]				<=== set to 100 for determine _BQC_use_index
[    3.336019] ACPI: Execute Method [\_SB_.PCI0.OVGA.DD02._BCM] (Node ffff88007b741c80)
[    3.339263] exregion-0302 [00] ex_system_io_space_han: System-IO (width 8) R/W 1 Address=0000000000000072
[    3.342167] exregion-0302 [00] ex_system_io_space_han: System-IO (width 8) R/W 1 Address=0000000000000073
[    3.345001]    video-0734 [00] video_init_brightness : found 10 brightness levels
[    3.347899]    utils-0286 [00] evaluate_integer      : Return value [131072]
[    3.350956] ACPI: Execute Method [\_SB_.PCI0.OVGA.DD02._BQC] (Node ffff88007b741ca8)
[    3.354598] exregion-0302 [00] ex_system_io_space_han: System-IO (width 32) R/W 1 Address=0000000000000080
[    3.456824]    utils-0286 [00] evaluate_integer      : Return value [30]				<=== set brightness value back to 30
[    3.460059] acpi device:28: registered as cooling_device0

The above acpi/video's behavior is normal, didn't see strange thing.
Please add 'video.use_bios_initial_backlight=0' then grab acpi debug log
again. You can find the similar log of DD02 device, this time the latest
'Return value' should be 100 like: Return value [100].

If 'video.use_bios_initial_backlight=0' works fine, the brightness
should set to 100%, means lightest.


Another dubious message in your dmesg is not from ACPI, it's a message
from i915 driver:
[    2.083603] i915: fixme: max PWM is zero

That means ODM set PWM register value default to zero, this register
used to control the the intensity of the backlight. I am still looking
what's the side effect that was caused by 'PWM = 0'.


Thanks a lot!
Joey Lee

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