From 95259e28ef047923258434898113d70c8e544eab Mon Sep 17 00:00:00 2001 From: Francis Rowe Date: Fri, 06 Nov 2015 17:43:29 -0500 Subject: convert documentation to texinfo --- (limited to 'docs/future/old.html') diff --git a/docs/future/old.html b/docs/future/old.html deleted file mode 100644 index 16f1121..0000000 --- a/docs/future/old.html +++ /dev/null @@ -1,319 +0,0 @@ - - - - - libreboot tutorials - - - - - - - - - - - -
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Development notes (old/obsolete notes)

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- For current notes, see index.html. -

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- These are old (obsolete) notes that mare kept because they might become useful again in the future. -

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Table of contents

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X60 native graphics initialization (with backlight controls)

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- - This is now obsolete. A better way was found (included in libreboot): http://review.coreboot.org/#/c/6731/ - -

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- Also check #5320_kernel312fix (to fix 3D on kernel 3.12/higher) -

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- The fix below was done on 5320/6 (from review.coreboot.org) but should work just fine on later versions of 5320. -

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- Native gpu init + backlight controls! (Fn keys). Also confirmed on X60 Tablet (1024x768) and X60 Tablet (1400x1050) -

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- Add backlight controls: in src/mainboard/lenovo/x60/devicetree.cb, change gpu_backlight to 0x879F879E -

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- That's all! This has also been backported into libreboot 5th release (line 1233 in src/mainboard/lenovo/x60/i915io.c). GNUtoo (Denis Carikli) - told me about the register BLC_PWM_CTL and that you could set it to control backlight. I read that address using devmem2 while running the VBIOS:
- # devmem2 0xe4361254 w -

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- The change is also included in libreboot 6. -

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- When doing this, it gave back that value. The same trick was used to get backlight controls for T60 (see #t60_native_notes). -

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Further notes

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- Reading 0xe4361254 (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). This person says - intel_backlight has different values and uses the register. devmem2 works, needs checking lspci -vv for where the memory is mapped, - which is different than on coreboot; mtjm found that it was 0xec061254 on his system (X60 Tablet), and the register value is different too. - 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.. -

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- Intel-gpu-tools may prove useful for further debugging: http://cgit.freedesktop.org/xorg/app/intel-gpu-tools/ -

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- 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. -

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- 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. - Note: this may not be correct; this person says that their understanding is based on how the Lenote yeeloong works. -

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- 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 -

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- phcoder (Vladimir Serbinenko) who is author of 5320 (review.coreboot.org) talks about 'duty cycle limit' and 'flickering frequency'. -

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T60 native graphics initialization (with backlight controls)

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- - This is now obsolete. A better way was found (included in libreboot): http://review.coreboot.org/#/c/6731/ - -

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- Also check #5320_kernel312fix (to fix 3D on kernel 3.12/higher) -

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- The fix below was done on an earlier version of 5345 changeset (review.coreboot.org), but should work on the current version. it is included in libreboot 6 -

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- Add backlight controls: in src/mainboard/lenovo/t60/devicetree.cb, change gpu_backlight to 0x58BF58BE -

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- Hold on! Check ../misc/index.html#get_edid_panelname to know what LCD panel you have. This is important for the next step! -

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Supported panels

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- ../hcl/index.html#supported_t60_list. -

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- See index.html#lcd_i945_incompatibility. -

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i945: 3D fix (based on 5927) for kernel 3.12+ on 5320

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- - This is now obsolete. Merged in coreboot: http://review.coreboot.org/#/c/5927/ - -

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This needs to be rewritten (or better organized, or deleted?). This is also now included in libreboot 6 (using the proper way, not the 7c0000 method which was a hack)

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- This was done on 5320/6 so far. The fix below is for 5320/6 which is now obsolete. This needs to be re-done for the latest version - of 5320. The fix below is (in practise) only for reference, therefore. -

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- See #x60_cb5927_testing for the original (and current) fix, for the replay code. Now we want - to implement that on top of http://review.coreboot.org/#/c/5320 - which is the current code for native graphics initialization on i945. -

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- src/northbridge/intel/i945/gma.c (using the 7c0000 hack) on 5320: 5320_7c0000_gma.c (rename it to gma.c, - replacing the current one). -

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- The above is a hack (as is the original). A better (more correct) method is implemented in later versions of 5927, so - that should also be adapted for 5320. For now, you can use the above fix. -

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- The correct way to do it is to set gtt address to (end of stolen memory - gtt size), which is what later versions of 5927 do (successfully). -

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- Here is some debugging output using intel_gpu_tools v1.2-1 (from trisquel repositories) using tool "intel_gtt": -

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i945/X60: Coreboot 5927 testing (3D fix for kernel 3.12+ on replay code)

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- - This is now obsolete. Merged in coreboot: http://review.coreboot.org/#/c/5927/ - -

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The latest version as-is (5927/11) has not been tested by me yet. Always boot with 'drm.debug=0x06' kernel parameter when testing this.

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- This is the fix for 3D on kernel 3.12 and higher on i945 (ThinkPad X60 in this case). This is for the replay code. - Libreboot 5th release has a version of this backported already (based on 5927/3 using the '7c0000' hack). -

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- - The replay code is obsolete (see 5320 changeset on review.coreboot.org for better version - which supports more systems/screens, and then 5345 for T60). Information here for reference since that is where the fix was first applied. - -

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- Read the information on http://review.coreboot.org/#/c/5927/. -

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- For historical purposes, here is a collection of IRC logs that once existed on this page, related to the issue: - kernel312_irc. -

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- PGETBL_CTL differs between VBIOS (-) and native graphics init (+).
- - - PGETBL_CTL: 0x3ffc0001
- + PGETBL_CTL: 0x3f800001 -

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GTT (graphics translation table) size is PGETBL_save, max 256 KiB. BSM (Base of Stolen Memory) is given by the bios.

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- Copyright © 2014, 2015 Francis Rowe <info@gluglug.org.uk>
- Permission is granted to copy, distribute and/or modify this document - under the terms of the GNU Free Documentation License, Version 1.3 - or any later version published by the Free Software Foundation; - with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. - A copy of the license can be found at ../gfdl-1.3.txt -

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- Updated versions of the license (when available) can be found at - https://www.gnu.org/licenses/licenses.html -

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- UNLESS OTHERWISE SEPARATELY UNDERTAKEN BY THE LICENSOR, TO THE - EXTENT POSSIBLE, THE LICENSOR OFFERS THE LICENSED MATERIAL AS-IS - AND AS-AVAILABLE, AND MAKES NO REPRESENTATIONS OR WARRANTIES OF - ANY KIND CONCERNING THE LICENSED MATERIAL, WHETHER EXPRESS, - IMPLIED, STATUTORY, OR OTHER. THIS INCLUDES, WITHOUT LIMITATION, - WARRANTIES OF TITLE, MERCHANTABILITY, FITNESS FOR A PARTICULAR - PURPOSE, NON-INFRINGEMENT, ABSENCE OF LATENT OR OTHER DEFECTS, - ACCURACY, OR THE PRESENCE OR ABSENCE OF ERRORS, WHETHER OR NOT - KNOWN OR DISCOVERABLE. WHERE DISCLAIMERS OF WARRANTIES ARE NOT - ALLOWED IN FULL OR IN PART, THIS DISCLAIMER MAY NOT APPLY TO YOU. -

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- TO THE EXTENT POSSIBLE, IN NO EVENT WILL THE LICENSOR BE LIABLE - TO YOU ON ANY LEGAL THEORY (INCLUDING, WITHOUT LIMITATION, - NEGLIGENCE) OR OTHERWISE FOR ANY DIRECT, SPECIAL, INDIRECT, - INCIDENTAL, CONSEQUENTIAL, PUNITIVE, EXEMPLARY, OR OTHER LOSSES, - COSTS, EXPENSES, OR DAMAGES ARISING OUT OF THIS PUBLIC LICENSE OR - USE OF THE LICENSED MATERIAL, EVEN IF THE LICENSOR HAS BEEN - ADVISED OF THE POSSIBILITY OF SUCH LOSSES, COSTS, EXPENSES, OR - DAMAGES. WHERE A LIMITATION OF LIABILITY IS NOT ALLOWED IN FULL OR - IN PART, THIS LIMITATION MAY NOT APPLY TO YOU. -

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- The disclaimer of warranties and limitation of liability provided - above shall be interpreted in a manner that, to the extent - possible, most closely approximates an absolute disclaimer and - waiver of all liability. -

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