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| author | Francis Rowe <info@gluglug.org.uk> | 2014-08-11 09:00:00 (EDT) |
|---|---|---|
| committer | Michał Masłowski <mtjm@mtjm.eu> | 2014-08-22 14:29:49 (EDT) |
| commit | 8df313c4d6607181576471e08d7e909c9c0f33e9 (patch) | |
| tree | 249f6003e3293fd4049ad57c267fa7ec1c4269e4 /docs/i945_backlight.html | |
| parent | 7eca665d684a734d55b0bb26c4f1831d399c5330 (diff) | |
| download | libreboot-r20140811.zip libreboot-r20140811.tar.gz libreboot-r20140811.tar.bz2 | |
Libreboot release 6 beta 5.r20140811
- build: added 'luks', 'lvm', 'cmosdump' and 'cmostest' to the list of
modules for grub.elf
- Documentation: added pics showing T60 unbricking (still need to
write a tutorial)
- build: include cmos.layout
(coreboot/src/mainboard/manufacturer/model/cmos.layout) files in
libreboot_bin
- Documentation: added ../docs/howtos/x60tablet_unbrick.html
- Documentation: added ../docs/howtos/t60_unbrick.html
- Documentation: added ../docs/howtos/t60_lcd_15.html
- Documentation: added ../docs/howtos/t60_security.html
- Documentation: added ../docs/howtos/t60_heatsink.html
- Documentation: Renamed RELEASE.html to release.html
- Documentation: removed pcmcia reference in x60_security.html (it's
cardbus)
- Documentation: added preliminary information about randomized seal
(for physical intrusion detection) in x60_security.html and
t60_security.html
- Documentation: added preliminary information about
preventing/mitigating cold-boot attack in x60_security.html and
t60_security.html
- Documentation: added info to ../docs/index.html#macbook21 warning
about issues with macbook21
- Documentation: X60/T60: added information about checking custom
ROM's using dd to see whether or not the top 64K region is
duplicated below top or not. Advise caution about this in the
tutorial that deals with flashing on top of Lenovo BIOS, citing the
correct dd commands necessary if it is confirmed that the ROM has
not been applied with dd yet. (in the case that the user compiled
their own ROM's from libreboot, without using the build scripts, or
if they forgot to use dd, etc).
- Split resources/libreboot/patch/gitdiff into separate patch files
(getcb script updated to accomodate this change).
- Re-added .git files to bucts
- Fixed the oversight where macbook21_firstflash wasn't included in
binary archives
Diffstat (limited to 'docs/i945_backlight.html')
| -rw-r--r-- | docs/i945_backlight.html | 118 |
1 files changed, 0 insertions, 118 deletions
diff --git a/docs/i945_backlight.html b/docs/i945_backlight.html deleted file mode 100644 index 1ce0137..0000000 --- a/docs/i945_backlight.html +++ /dev/null @@ -1,118 +0,0 @@ -<!DOCTYPE html> -<html lang="en"> -<head> - <meta charset="utf-8"> - <title>i945 backlight in libreboot</title> - - <style type="text/css"> - body { - font-family: sans-serif; - font-size: 1em; - background: #fff; - color: #000; - } - - </style> - - <meta name="viewport" content="width=device-width, initial-scale=1.0"> - <meta name="author" content="glugman"> - <meta name="description" content="tutorials for libreboot, the reboot library."> - <meta name="robots" content="all"> -</head> - -<body> - - <header> - <h1 id="pagetop">i945 backlight controls on X60/T60</h1> - </header> - - <p> - <a href="index.html">back to index</a> - </p> - -<hr/> - - <h2>Contents</h2> - <ul> - <li><a href="#x60_native_notes">X60 native graphics initialization (backlight controls)</a></li> - <li><a href="#t60_native_notes">T60 native graphics initialization (backlight controls)</a></li> - </ul> - -<hr/> - - <h1 id="x60_native_notes">X60 native graphics initialization (with backlight controls)</h1> - <p> - <b>The fix below was done on 5320/6 (review.coreboot.org) under src/mainboard/lenovo/x60/devicetree.cb</b> - </p> - <p> - Works on the ThinkPad X60, X60s and X60 Tablet. This change is also included by default in libreboot 6th release. - </p> - <p> - <b>Add backlight controls:</b> in <i>src/mainboard/lenovo/x60/devicetree.cb</i>, change <b>gpu_backlight</b> to <b>0x879F879E</b> - </p> - <p> - That's all! <b>This was also backported into libreboot 5th release (line 1233 in src/mainboard/lenovo/x60/i915io.c)</b>. GNUtoo (Denis Carikli) - told me about the register <b>BLC_PWM_CTL</b> and that you could set it to control backlight. I read that address using devmem2 while running the VBIOS:<br/> - <b># devmem2 0xe4361254 w</b> - </p> - <p> - When doing this, it gave back that value. The same trick was used to get backlight controls for T60 (see <a href="#t60_native_notes">#t60_native_notes</a>). - </p> - - <h2>Further notes (as of 6th libreboot release, initial revision)</h2> - <p> - Reading <b>0xe4361254</b> (address) in Lenovo BIOS always yields FFFFFFFF, even when writing to it (and writing to it doesn't affect brightness controls). - 'mtjm' on IRC found that the buttons (Fn keys) control /sys/class/backlight/acpi_video0 which has no affect on 61254 (BLC_PWM_CTL). He says - intel_backlight has different values and uses the register. devmem2 works, needs checking <b>lspci -vv</b> for where the memory is mapped, - which is different than on coreboot; mtjm found that it was 0xec061254 on his machine (X60 Tablet), and the register value is different too. - <b>This is relevant, because we still don't know how backlight controls are actually handled. We got it working by accident. We need to know more.</b>. - </p> - <p> - Intel-gpu-tools may prove useful for further debugging: <a href="http://cgit.freedesktop.org/xorg/app/intel-gpu-tools/">http://cgit.freedesktop.org/xorg/app/intel-gpu-tools/</a> - </p> - <p> - mtjm says 0xe4300000 is an MMIO region of the gpu (lspci -vv shows it), 0x61254 (BLC_PWM_CTL) is a documented register. Searching the kernel driver for backlight - shows that in intel_panel.c this register is used (there is an XXX comment about finding the right value, where recent kernels get it from. - </p> - <p> - What we want to do is calculate a good value, instead of setting it in devicetree.cb. mtjm says about backlight physics: - it has a light source , uses pulse width modulation (PWM) to turn it on/off, dimming is done by spending less time on. - <b>Note: this may not be correct; he says his understanding is based on how the Lenote yeeloong works</b>. - </p> - <p> - mtjm goes on to say, that the register specifies the frequency used for PWM in its depending on the GPU core frequency, so it - might be possible to calculate it without hardcoded laptop-specific values. Therefore, I am supposed to find out the 'display core frequency' - (mtjm says there might be a register for it; also, it might be in 5320 or the replay code) and the PWM modulation frequency. - https://en.wikipedia.org/wiki/Backlight#Flicker_due_to_backlight_dimming - </p> - <p> - phcoder (Vladimir Serbinenko) who is author of 5320 (review.coreboot.org) talks about 'duty cycle limit' and 'flickering frequency'. - </p> - - <p><a href="#pagetop">Back to top of page</a></p> - -<hr/> - - <h1 id="t60_native_notes">T60 native graphics initialization (with backlight controls)</h1> - <p> - <b>The fix below was done on an earlier version of 5345 (review.coreboot.org) cherry-picked on top of 5320 checkout, but also works on the current version.</b> - </p> - <p> - This change is also included by default in libreboot 6th release. - </p> - <p> - <b>Add backlight controls:</b> in <i>src/mainboard/lenovo/t60/devicetree.cb</i>, change <b>gpu_backlight</b> to <b>0x58BF58BE</b> - </p> - - <p><a href="#pagetop">Back to top of page</a></p> - -<hr/> - - <p> - Copyright © 2014 Francis Rowe, All Rights Reserved.<br/> - See <a href="license.html">license.html</a> for license conditions. - </p> - -</body> -</html> - |