ACPI problem: screen brightness controls stop functioning after waking from standby

Report a bug. You may need to unload and load a module. It obviously the acpi like being hibernated. Can you give the output of:

lsb_release -a; lsmod

Thanks

PORTEGE-R835:~$ lsb_release -a; lsmod
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 11.04
Release: 11.04
Codename: natty
Module Size Used by
sha256_generic 21031 2
cryptd 20510 0
aes_x86_64 17208 160
aes_generic 38279 1 aes_x86_64
binfmt_misc 17565 1
parport_pc 36959 0
ppdev 17113 0
dm_crypt 22993 1
vboxnetadp 13340 0
vboxnetflt 28297 0
vboxdrv 252684 2 vboxnetadp,vboxnetflt
snd_hda_codec_hdmi 28167 1
snd_hda_codec_realtek 336771 1
joydev 17606 0
snd_hda_intel 33176 3
arc4 12529 2
snd_hda_codec 103804 3 snd_hda_codec_hdmi,snd_hda_codec_realtek,snd_hda_intel
snd_hwdep 13604 1 snd_hda_codec
snd_pcm 96391 3 snd_hda_codec_hdmi,snd_hda_intel,snd_hda_codec
uvcvideo 72195 0
snd_seq_midi 13324 0
videodev 82052 1 uvcvideo
snd_rawmidi 30486 1 snd_seq_midi
snd_seq_midi_event 14899 1 snd_seq_midi
v4l2_compat_ioctl32 17078 1 videodev
snd_seq 61621 2 snd_seq_midi,snd_seq_midi_event
iwlagn 333716 0
snd_timer 29602 2 snd_pcm,snd_seq
snd_seq_device 14462 3 snd_seq_midi,snd_rawmidi,snd_seq
snd 67382 16 snd_hda_codec_hdmi,snd_hda_codec_realtek,snd_hda_intel,snd_hda_codec,snd_hwdep,snd_pcm,snd_rawmidi,snd_seq,snd_timer,snd_seq_device
iwlcore 167502 1 iwlagn
mac80211 294370 2 iwlagn,iwlcore
psmouse 73535 0
serio_raw 13166 0
cfg80211 178528 3 iwlagn,iwlcore,mac80211
soundcore 12680 1 snd
snd_page_alloc 18529 2 snd_hda_intel,snd_pcm
toshiba_acpi 14180 0
sparse_keymap 13898 1 toshiba_acpi
lp 17825 0
parport 46458 3 parport_pc,ppdev,lp
i915 515121 2
e1000e 159096 0
ahci 25951 2
drm_kms_helper 42136 1 i915
libahci 26642 1 ahci
drm 227534 3 i915,drm_kms_helper
sdhci_pci 13989 0
xhci_hcd 77643 0
sdhci 27387 1 sdhci_pci
i2c_algo_bit 13400 1 i915
video 19438 1 i915

Well that came out terrible. Here's a pastebin that's easier to read: http://pastebin.com/eiTtwhYY

After you wake up the system, run:

sudo modprobe -r toshiba_acpi; sleep 2; sudo modprobe toshiba_acpi

Does it work ok after that?

Nope.

kern.log:
Sep 19 16:10:21 PORTEGE-R835 kernel: [ 197.347094] input: Toshiba input device as /devices/virtual/input/input12

Sep 19 16:10:21 PORTEGE-R835 kernel: [ 197.347248] toshiba_acpi: Toshiba Laptop ACPI Extras version 0.19

Sep 19 16:10:21 PORTEGE-R835 kernel: [ 197.347256] toshiba_acpi: HCI method: \_SB_.VALZ.GHCI

Sep 19 16:10:21 PORTEGE-R835 kernel: [ 197.351364] Registered led device: toshiba::illumination

Sep 19 16:10:24 PORTEGE-R835 kernel: [ 200.089937] ACPI: Failed to switch the brightness
Sep 19 16:10:24 PORTEGE-R835 kernel: [ 200.288581] ACPI: Failed to switch the brightness

I just bought the same laptop, and installed debian on it with similar issue of brightness not working after waking from sleep.

I also updated BIOS in Windows with files from toshiba, still the same problem, but I noticed in the BIOS, you can set brightness, cpu performance for non ACPI OS. After
setting brightness to medium, waking up from sleep doesn't give me bright LCD,
but the brightness can't adjusted, and cpu frequency stays low (800 MHz). Doe it
look like after resumption acpi somehow thinks the OS doesn't support ACPI?

Also hibernate and wake up things are working again...

I have the exact same issue here.

[ 1789.115409] ACPI: Failed to switch the brightness
[ 1789.532438] ACPI: Failed to switch the brightness
[ 1789.730896] ACPI: Failed to switch the brightness
[ 1789.911127] ACPI: Failed to switch the brightness

anybody figured any workarounds yet?

It is the same issue that I was facing in my screen brightness control but you can see some guide now here https://calculatorsbag.com/ to solve this issue.