From 3b55fca2c913f5875860fc1397f0b316aa249727 Mon Sep 17 00:00:00 2001 From: Leah Rowe Date: Tue, 31 Dec 2024 15:44:26 +0000 Subject: [PATCH] document t480/3050 pmc config Signed-off-by: Leah Rowe --- site/docs/install/dell3050.md | 22 ++++++++++++++++++++++ site/docs/install/t480.md | 22 ++++++++++++++++++++++ 2 files changed, 44 insertions(+) diff --git a/site/docs/install/dell3050.md b/site/docs/install/dell3050.md index c41487e..2b5f9f3 100644 --- a/site/docs/install/dell3050.md +++ b/site/docs/install/dell3050.md @@ -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: + + + +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 ------------ diff --git a/site/docs/install/t480.md b/site/docs/install/t480.md index 66be2fe..eada576 100644 --- a/site/docs/install/t480.md +++ b/site/docs/install/t480.md @@ -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: + + + +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 ------------