libreboot tutorials
*******************

Development notes
*****************

These are development notes, for future use. For old (obselete) notes, see old.html.

Or go back to main task list (../tasks.html).

Table of contents
*****************

  * Standard test

  * T60 cpu microcode

  * i945 VRAM size

  * LCD panels on i945 - fix incompatible panels

  * i945 X60/T60 VBT implementation (experimental: testing)

  * IntelVbtTool results

  * Fallback patches for i945

standard test
*************

These logs are usually obtained when testing changes related to graphics on i945 (X60 and T60).

  * Make a copy of these files:

       * /var/log/dmesg

       * /var/log/kern.log

       * /var/log/Xorg.0.log

       * /proc/ioports

       * /proc/iomem

       * /sys/class/drm/card0/error

  * Record these outputs:

       * sudo intel_reg_dumper

       * uname -r

       * lspci -vvvvnnnnxxxx

       * sudo modprobe msr

       * sudo inteltool -a

       * sudo cbmem -c

  * Try some 3D games with latest kernel.

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T60 cpu microcode
*****************

TODO: T60: find (for rare buggy CPUs that are unstable without microcode updates) if there is a workaround (patched kernel, special parameter, etc) So far, only 1 processor has been found to have issues. See microcode errata sheets http://download.intel.com/design/mobile/SPECUPDT/31407918.pdf and http://download.intel.com/design/mobile/SPECUPDT/30922214.pdf and then look at the debugging results collected in t7200q (../t7200q) directory (q means quirk).

Every other T7200 tested so far has worked without microcode updates.

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i945 VRAM size
**************

Apparently, only 8MB VRAM is available on i945 GPUs (though it could do 64MB):
 phcoder: No. Hardware default is 8 MiB. When I wanted to make it configurable, I saw that docs mention only one other alternative: 1MiB. Later isn't event enough for 1024x768 at 24bpp without any acceleration or double buffering. It's possible that there are undocumented values. Which options do you have in vendor BIOS? How to find out how much vram you have:
 phcoder: TOM - BSM
 phcoder: check what vendor BIOS offers as options
 fchmmr: I thought it could do 64MB usually
 phcoder: not accorging to doc.
 phcoder: see mobile-945-express-chipset-datasheet page 93
 phcoder: see also src/northbridge/intel/i945/{early_init,northbridge,gma}.c
 fchmmr: "011 = DVMT (UMA) mode, 8 MB of memory pre-allocated for
 fchmmr: frame buffer."
 fchmmr: "Others - reserved"
 phcoder: the easiest way is a loop at this position which tries different values and reads (and prints) BSM with them
 stefanct: fchmmr: they suggest that you change the value and look how BSM reacts to that
 stefanct: as they pointed out earlier vram size = TOM - BSM
 stefanct: different values of GMS
 stefanct: phcoder: hm... this could be a hint. look at the text description of TOLUD at page 103
 stefanct: it mentions 64 MB in the text about BSM as well
 stefanct: table 18...
 phcoder: stefanct: I have a guess which value make is 64 but I will not tell to avoid skewing test results
 stefanct: phcoder: sure... i assumed you were not sure if it supports it at all. testing it properly is of course a good idea :)
 stefanct: test the various possible (but reserved) values of GMS and see what the resulting VRAM size is
 fchmmr: so, TOM - BSM

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LCD panels on i945 - fix incompatible panels
********************************************

Fix T60 issues (see incompatible panels listed at ../hcl/index.html#supported_t60_list).

Run that tool (resources/utilities/i945gpu/intel-regs.py) as root on systems with the offending panels in:

  * Coreboot (or libreboot, whatever) with VBIOS (disable native graphics also)

  * (Factory BIOS also?)

This shows values in devicetree.cb and src/northbridge/intel/i945/gma.c, the idea is that you run it on factory bios or vbios and that it will (might) show different values: then you try those in the native graphics (in libreboot).

Other values/registers might also need to be added to the script for these tests.

check if intel_bios_reader from intel-gpu-tools reports the same value (BIOS has a hardcoded value) for PWM modulation frequency. This file can read the VBIOS (64K dump).

Check other tools in intel-gpu-tools aswell, compare outputs. Possibly add more information to intel-regs.py output (submit changes to mtjm). Do oprom trace / replay (http://www.coreboot.org/User:GNUtoo#How_to_get_rid_of_the_vbios_of_the_x60_.5BNew_Version.5D)

Study how EDID works and how gma.c handles it.

Original getregs.py script can be found at http://hg.mtjm.eu/scripts/file/tip/intel-regs.py written by Michał Masłowski.

About fixing remaining LCD panels on 5345:
 'polarity' is mentioned in coreboot log (cbmem -c). compare output (with working and non-working panel). (and see the other notes in docs/future/index.html)

There was a theory that working panels are 6bpc (bits per colour) and nonworking are 8bpc, but all EDIDs that we have here are for 6bpc panels.

We should compare coreboot logs (from cbmem -c from systems with working and nonworking panels.

How to dump EDID:

# apt-get install i2c-tools
 # modprobe i2c-dev
 Find out the correct ID to use:
 # i2cdetect -l
 Example:
 # i2cdump -y 2 0x50

Working panel: EDID dump from LG-Philips LP150E05-A2K1:

No size specified (using byte-data access)
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f    0123456789abcdef
00: XX ff ff ff ff ff ff 00 30 ae 43 40 00 00 00 00    X.......0?C@....
10: 00 0f 01 03 80 1e 17 78 ea af 00 99 58 53 8c 2a    .??????x??.?XS?*
20: 25 50 54 21 08 00 81 80 01 01 01 01 01 01 01 01    %PT!?.??????????
30: 01 01 01 01 01 01 30 2a 78 20 51 1a 10 40 30 70    ??????0*x Q??@0p
40: 13 00 31 e4 10 00 00 18 28 23 78 20 51 1a 10 40    ?.1??..?(#x Q??@
50: 30 70 13 00 31 e4 10 00 00 18 00 00 00 0f 00 90    0p?.1??..?...?.?
60: 43 32 90 43 28 14 06 00 32 0c 00 00 00 00 00 fe    C2?C(??.2?.....?
70: 00 4c 50 31 35 30 45 30 35 2d 41 32 0a 20 00 9b    .LP150E05-A2? .?
80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
90: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
a0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
b0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
c0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
d0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
e0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
f0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................

Working panel: EDID dump from Boe-Hydis HT14P12-100 FRU: 13N7061 (Inverter FRU: 41W1010)

     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f    0123456789abcdef
00: 00 ff ff ff ff ff ff 00 30 ae 22 40 00 00 00 00    ........0?"@....
10: 00 0f 01 03 80 1c 15 78 ea af 40 95 56 4a 8f 25    .??????x??@?VJ?%
20: 20 50 54 21 08 00 81 80 01 01 01 01 01 01 01 01     PT!?.??????????
30: 01 01 01 01 01 01 30 2a 78 20 51 1a 10 40 30 70    ??????0*x Q??@0p
40: 13 00 1d d6 10 00 00 19 25 23 78 20 51 1a 10 40    ?.???..?%#x Q??@
50: 30 70 13 00 1d d6 10 00 00 19 00 00 00 0f 00 90    0p?.???..?...?.?
60: 43 32 90 43 28 0f 01 00 09 e5 00 00 00 00 00 fe    C2?C(??.??.....?
70: 00 48 54 31 34 50 31 32 2d 31 30 30 0a 20 00 3f    .HT14P12-100? .?
80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
90: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
a0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
b0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
c0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
d0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
e0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
f0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................

LTN141XA-L01: revert to libreboot git commit c943281 to see this

Non-working panel: EDID dump from Samsung LTN150XG-L08:

     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f    0123456789abcdef
00: 00 ff ff ff ff ff ff 00 30 ae 40 40 00 00 00 00    ........0?@@....
10: 00 0f 01 03 80 1f 17 78 ea 2d 05 97 57 51 8a 27    .??????x?-??WQ?'
20: 23 50 54 21 08 00 01 01 01 01 01 01 01 01 01 01    #PT!?.??????????
30: 01 01 01 01 01 01 64 19 00 40 41 00 26 30 18 88    ??????d?.@A.&0??
40: 36 00 30 e4 10 00 00 19 28 15 00 40 41 00 26 30    6.0??..?(?.@A.&0
50: 18 88 36 00 30 e4 10 00 00 19 00 00 00 0f 00 61    ??6.0??..?...?.a
60: 43 32 61 43 28 14 01 00 4c a3 58 47 00 00 00 fe    C2aC(??.L?XG...?
70: 00 4c 54 4e 31 35 30 58 47 2d 4c 30 38 0a 00 6d    .LTN150XG-L08?.m
80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
90: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
a0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
b0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
c0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
d0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
e0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
f0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................

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i945 gfx: X60/T60 VBT implementation (experimental: testing)
************************************************************

intel_bios_dumper in intel-gpu-tools seems interesting.

Use 'drm.debug=0x06' kernel parameter when booting in grub!

Before each test run, boot a live USB and delete the old logs in /var/log (kernel log, xorg log, dmesg and so on).

Load (from the ROM) the runningvga.bin for each LCD panel on each system; do not execute it, only load it! (coreboot will have to be modified). Rename the ROM appropriately, based on the system name and the panel name. coreboot_nativegfx_5868_plusrunningvga_t60_14_LTD141ECMB.rom, for instance. Keep a copy for later use.

You are supposed to:

  * enable native graphics in menuconfig

  * include the self-modified VGA ROM (load, but not execute) - for reverse engineering the correct VBT tables.

With each boot, make notes about what you see and get logs using the standard test. You will need the files from #intelvbttool_results for each system.

Results (# means untested):

  * X60/X60s:

       * TMD-Toshiba LTD121ECHB: #

       * CMO N121X5-L06: #

       * Samsung LTN121XJ-L07: #

       * BOE-Hydis HT121X01-101: #

  * X60T XGA:

       * BOE-Hydis HV121X03-100: #

  * X60T SXGA+:

       * BOE-Hydis HV121P01-100: #

  * T60 14" XGA:

       * Samsung LTN141XA-L01: #

       * CMO N141XC: #

       * BOE-Hydis HT14X14: #

       * TMD-Toshiba LTD141ECMB: #

  * T60 14" SXGA+

       * TMD-Toshiba LTD141EN9B: #

       * Samsung LTN141P4-L02: #

       * Boe-Hydis HT14P12: #

  * T60 15" XGA

       * Samsung LTN150XG-L08: #

       * LG-Philips LP150X09: #

       * 13N7068 (IDtech): #

       * 13N7069 (CMO): #

  * T60 15" SXGA+

       * LG-Philips LP150E05-A2K1: #

       * BOE-Hydis HV150P01-100: #

  * T60 15" UXGA

       * BOE-Hydis HV150UX1-100: #

       * IDTech N150U3-L01: #

       * BOE-Hydis HV150UX1-102: #

  * T50 15" QXGA

       * IDtech IAQX10N: #

       * IDtech IAQX10S: #

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intelvbttool test results (VGA ROM dumps)
*****************************************

The VBIOS on i945 (intel gpu) platforms is self-modifying; that is, its contents change when you run it. intelvbttool takes a dump of the currently running vbios, and parses it.

The idea is that we can extract the VBT tables using this knowledge, on the X60, X60 Tablet and T60 (Intel GPU).

Here is an example of how VBT was implemented on the ThinkPad X230: http://review.coreboot.org/#/c/5396.

You'll need to build a T60 ROM with SeaBIOS and the VGA ROM (for Intel GPU). An X60 ROM is also needed (same configuration, using the VGA ROM for X60).

T60 has DVI on its dock, make sure that the dock is attached when getting this output.

Get intelvbttool here: http://review.coreboot.org/#/c/5842 (util/intelvbttool).

Now dump a copy of the running VGA BIOS: $ sudo dd if=/dev/mem bs=64k of=runningvga.bin skip=12 count=1
 Then do (and record the output):
 $ ./intelvbttool runningvga.bin > intelvbttool_out

Backup both files (runningvga.bin and intelvbttool_out), renaming them to match the system and LCD panel used. ../misc/index.html#get_edid_panelname will show you how to get the name (model) of the LCD panel used.

Test results (# means untested and all had docks, unless noted).
================================================================

  * X60/X60s:

       * TMD-Toshiba LTD121ECHB: #

       * CMO N121X5-L06: #

       * Samsung LTN121XJ-L07: #

       * BOE-Hydis HT121X01-101: #

  * X60T XGA (1024x768):

       * BOE-Hydis HV121X03-100: #

  * X60T SXGA+ (1400x1050):

       * BOE-Hydis HV121P01-100: #

  * T60 14" XGA (1024x768):

       * Samsung LTN141XA-L01: #

       * CMO N141XC: #

       * BOE-Hydis HT14X14: #

       * TMD-Toshiba LTD141ECMB: #

  * T60 14" SXGA+ (1400x1050):

       * TMD-Toshiba LTD141EN9B: #

       * Samsung LTN141P4-L02: #

       * Boe-Hydis HT14P12: #

  * T60 15" XGA (1024x768):

       * Samsung LTN150XG-L08: #

       * LG-Philips LP150X09: #

       * 13N7068 (IDtech): #

       * 13N7069 (CMO): #

  * T60 15" SXGA+ (1400x1050):

       * LG-Philips LP150E05-A2K1: #

       * BOE-Hydis HV150P01-100: #

  * T60 15" UXGA (1600x1200):

       * BOE-Hydis HV150UX1-100: #

       * IDTech N150U3-L01: #

       * BOE-Hydis HV150UX1-102: #

  * T60 15" QXGA (2048x1536):

       * IDtech IAQX10N: #

       * IDtech IAQX10S: #

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Fallback patches
****************

  * Todo: test gnutoo's fallback patches: http://www.coreboot.org/Fallback_mechanism (some parts use systemd. adapt for upstart, which is what trisquel uses)
      see this IRC log (gnutoo_fallback_patch) (warning, not cleaned up)

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Other - unlisted (low priority)
*******************************

  * PTE errors still exist on i945 with 6718 (which is merged). http://review.coreboot.org/#/c/6718/

       * dmesg (future/dumps/pte_x60_6718/dmesg)

       * kern.log (future/dumps/pte_x60_6718/kern.log)

       * This doesn't seem to cause any issues for general use.

  * Implement INT 10H support in i945 native graphics. (this will be a lot of work. SeaBIOS has code for some geode boards, to get a general idea).

  * T60 15" QXGA (2048x1536): fixed issue where GRUB wouldn't show any graphics. (Not many people have this panel)

       * It might be the same issue I ran into with Paul on the X60 (not enough memory being allocated) since the same code works on T60 SXGA+ and UXGA, where GRUB actually display graphics.

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Copyright © 2014, 2015 Francis Rowe <info@gluglug.org.uk>
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