android_kernel_xiaomi_sm8350/Documentation/power/video.txt

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Video issues with S3 resume
~~~~~~~~~~~~~~~~~~~~~~~~~~~
2003-2005, Pavel Machek
During S3 resume, hardware needs to be reinitialized. For most
devices, this is easy, and kernel driver knows how to do
it. Unfortunately there's one exception: video card. Those are usually
initialized by BIOS, and kernel does not have enough information to
boot video card. (Kernel usually does not even contain video card
driver -- vesafb and vgacon are widely used).
This is not problem for swsusp, because during swsusp resume, BIOS is
run normally so video card is normally initialized. It should not be
problem for S1 standby, because hardware should retain its state over
that.
There are a few types of systems where video works after S3 resume:
(1) systems where video state is preserved over S3.
(2) systems where it is possible to call the video BIOS during S3
resume. Unfortunately, it is not correct to call the video BIOS at
that point, but it happens to work on some machines. Use
acpi_sleep=s3_bios.
(3) systems that initialize video card into vga text mode and where
the BIOS works well enough to be able to set video mode. Use
acpi_sleep=s3_mode on these.
(4) on some systems s3_bios kicks video into text mode, and
acpi_sleep=s3_bios,s3_mode is needed.
(5) radeon systems, where X can soft-boot your video card. You'll need
a new enough X, and a plain text console (no vesafb or radeonfb). See
http://www.doesi.gmxhome.de/linux/tm800s3/s3.html for more information.
Alternatively, you should use vbetool (6) instead.
(6) other radeon systems, where vbetool is enough to bring system back
to life. It needs text console to be working. Do vbetool vbestate
save > /tmp/delme; echo 3 > /proc/acpi/sleep; vbetool post; vbetool
vbestate restore < /tmp/delme; setfont <whatever>, and your video
should work.
(7) on some systems, it is possible to boot most of kernel, and then
POSTing bios works. Ole Rohne has patch to do just that at
http://dev.gentoo.org/~marineam/patch-radeonfb-2.6.11-rc2-mm2.
(8) on some systems, you can use the video_post utility mentioned here:
http://bugzilla.kernel.org/show_bug.cgi?id=3670. Do echo 3 > /sys/power/state
&& /usr/sbin/video_post - which will initialize the display in console mode.
If you are in X, you can switch to a virtual terminal and back to X using
CTRL+ALT+F1 - CTRL+ALT+F7 to get the display working in graphical mode again.
Now, if you pass acpi_sleep=something, and it does not work with your
bios, you'll get a hard crash during resume. Be careful. Also it is
safest to do your experiments with plain old VGA console. The vesafb
and radeonfb (etc) drivers have a tendency to crash the machine during
resume.
You may have a system where none of above works. At that point you
either invent another ugly hack that works, or write proper driver for
your video card (good luck getting docs :-(). Maybe suspending from X
(proper X, knowing your hardware, not XF68_FBcon) might have better
chance of working.
Table of known working notebooks:
Model hack (or "how to do it")
------------------------------------------------------------------------------
Acer Aspire 1406LC ole's late BIOS init (7), turn off DRI
Acer TM 242FX vbetool (6)
Acer TM C110 video_post (8)
Acer TM C300 vga=normal (only suspend on console, not in X), vbetool (6) or video_post (8)
Acer TM 4052LCi s3_bios (2)
Acer TM 636Lci s3_bios,s3_mode (4)
Acer TM 650 (Radeon M7) vga=normal plus boot-radeon (5) gets text console back
Acer TM 660 ??? (*)
Acer TM 800 vga=normal, X patches, see webpage (5) or vbetool (6)
Acer TM 803 vga=normal, X patches, see webpage (5) or vbetool (6)
Acer TM 803LCi vga=normal, vbetool (6)
Arima W730a vbetool needed (6)
Asus L2400D s3_mode (3)(***) (S1 also works OK)
Asus L3350M (SiS 740) (6)
Asus L3800C (Radeon M7) s3_bios (2) (S1 also works OK)
Asus M6887Ne vga=normal, s3_bios (2), use radeon driver instead of fglrx in x.org
Athlon64 desktop prototype s3_bios (2)
Compal CL-50 ??? (*)
Compaq Armada E500 - P3-700 none (1) (S1 also works OK)
Compaq Evo N620c vga=normal, s3_bios (2)
Dell 600m, ATI R250 Lf none (1), but needs xorg-x11-6.8.1.902-1
Dell D600, ATI RV250 vga=normal and X, or try vbestate (6)
Dell D610 vga=normal and X (possibly vbestate (6) too, but not tested)
Dell Inspiron 4000 ??? (*)
Dell Inspiron 500m ??? (*)
Dell Inspiron 510m ???
Dell Inspiron 600m ??? (*)
Dell Inspiron 8200 ??? (*)
Dell Inspiron 8500 ??? (*)
Dell Inspiron 8600 ??? (*)
eMachines athlon64 machines vbetool needed (6) (someone please get me model #s)
HP NC6000 s3_bios, may not use radeonfb (2); or vbetool (6)
HP NX7000 ??? (*)
HP Pavilion ZD7000 vbetool post needed, need open-source nv driver for X
HP Omnibook XE3 athlon version none (1)
HP Omnibook XE3GC none (1), video is S3 Savage/IX-MV
IBM TP T20, model 2647-44G none (1), video is S3 Inc. 86C270-294 Savage/IX-MV, vesafb gets "interesting" but X work.
IBM TP A31 / Type 2652-M5G s3_mode (3) [works ok with BIOS 1.04 2002-08-23, but not at all with BIOS 1.11 2004-11-05 :-(]
IBM TP R32 / Type 2658-MMG none (1)
IBM TP R40 2722B3G ??? (*)
IBM TP R50p / Type 1832-22U s3_bios (2)
IBM TP R51 none (1)
IBM TP T30 236681A ??? (*)
IBM TP T40 / Type 2373-MU4 none (1)
IBM TP T40p none (1)
IBM TP R40p s3_bios (2)
IBM TP T41p s3_bios (2), switch to X after resume
IBM TP T42 s3_bios (2)
IBM ThinkPad T42p (2373-GTG) s3_bios (2)
IBM TP X20 ??? (*)
IBM TP X30 s3_bios (2)
IBM TP X31 / Type 2672-XXH none (1), use radeontool (http://fdd.com/software/radeon/) to turn off backlight.
IBM TP X32 none (1), but backlight is on and video is trashed after long suspend
IBM Thinkpad X40 Type 2371-7JG s3_bios,s3_mode (4)
Medion MD4220 ??? (*)
Samsung P35 vbetool needed (6)
Sharp PC-AR10 (ATI rage) none (1)
Sony Vaio PCG-C1VRX/K s3_bios (2)
Sony Vaio PCG-F403 ??? (*)
Sony Vaio PCG-N505SN ??? (*)
Sony Vaio vgn-s260 X or boot-radeon can init it (5)
Toshiba Libretto L5 none (1)
Toshiba Satellite 4030CDT s3_mode (3)
Toshiba Satellite 4080XCDT s3_mode (3)
Toshiba Satellite 4090XCDT ??? (*)
Toshiba Satellite P10-554 s3_bios,s3_mode (4)(****)
Toshiba M30 (2) xor X with nvidia driver using internal AGP
Uniwill 244IIO ??? (*)
Known working desktop systems
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Mainboard Graphics card hack (or "how to do it")
------------------------------------------------------------------------------
Asus A7V8X nVidia RIVA TNT2 model 64 s3_bios,s3_mode (4)
(*) from http://www.ubuntulinux.org/wiki/HoaryPMResults, not sure
which options to use. If you know, please tell me.
(***) To be tested with a newer kernel.
(****) Not with SMP kernel, UP only.
VBEtool details
~~~~~~~~~~~~~~~
(with thanks to Carl-Daniel Hailfinger)
First, boot into X and run the following script ONCE:
#!/bin/bash
statedir=/root/s3/state
mkdir -p $statedir
chvt 2
sleep 1
vbetool vbestate save >$statedir/vbe
To suspend and resume properly, call the following script as root:
#!/bin/bash
statedir=/root/s3/state
curcons=`fgconsole`
fuser /dev/tty$curcons 2>/dev/null|xargs ps -o comm= -p|grep -q X && chvt 2
cat /dev/vcsa >$statedir/vcsa
sync
echo 3 >/proc/acpi/sleep
sync
vbetool post
vbetool vbestate restore <$statedir/vbe
cat $statedir/vcsa >/dev/vcsa
rckbd restart
chvt $[curcons%6+1]
chvt $curcons
Unless you change your graphics card or other hardware configuration,
the state once saved will be OK for every resume afterwards.
NOTE: The "rckbd restart" command may be different for your
distribution. Simply replace it with the command you would use to
set the fonts on screen.