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document t480/3050 pmc config 

Signed-off-by: Leah Rowe <info@minifree.org>
master
Leah Rowe 2024-12-31 15:44:26 +00:00
parent 32c80dae9c
commit 3b55fca2c9
2 changed files with 44 additions and 0 deletions
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22
site/docs/install/dell3050.md
View File

@ -178,6 +178,28 @@ service jumper is set).
Errata
======
Power-on after power failure
----------------------------
Older Libreboot revisions made this machine always turn on, when plugging in
a power supply (charger brick), if a previous power loss was observed. This is
because coreboot sets a special register in the PMC that configures such
behaviour, but it was hardcoded to always-on. This is undesirable for most
people, so Libreboot 20241206 *revision 8* and newer releases contain the
following modification:
<https://browse.libreboot.org/lbmk.git/commit/?id=09a01477df67e3ddc36e11123c537332d7813c50>
If you wish to modify this behaviour again, you could modify the patch
referenced there; the actual location of the `.patch` file may change over
time, so you can basically just modify the coreboot source file
at `src/soc/intel/common/block/pmc/pmclib.c` (for the coreboot tree
under `src/coreboot/` in lbmk, pertaining to your board, which can be determined
by reading the `tree` variable in your board's `target.cfg` file within lbmk).
Use the patch as reference, to modify the coreboot behaviour as you wish, and
re-compile [from source](../build/).
TPM disabled
------------

22
site/docs/install/t480.md
View File

@ -522,6 +522,28 @@ Errata
Some features either don't work, or are untested, when running Libreboot on
the ThinkPad T480 or T480s.
Power-on after power failure
----------------------------
Older Libreboot revisions made this machine always turn on, when plugging in
a power supply (charger brick), if a previous power loss was observed. This is
because coreboot sets a special register in the PMC that configures such
behaviour, but it was hardcoded to always-on. This is undesirable for most
people, so Libreboot 20241206 *revision 8* and newer releases contain the
following modification:
<https://browse.libreboot.org/lbmk.git/commit/?id=09a01477df67e3ddc36e11123c537332d7813c50>
If you wish to modify this behaviour again, you could modify the patch
referenced there; the actual location of the `.patch` file may change over
time, so you can basically just modify the coreboot source file
at `src/soc/intel/common/block/pmc/pmclib.c` (for the coreboot tree
under `src/coreboot/` in lbmk, pertaining to your board, which can be determined
by reading the `tree` variable in your board's `target.cfg` file within lbmk).
Use the patch as reference, to modify the coreboot behaviour as you wish, and
re-compile [from source](../build/).
TPM disabled
------------