From 32a9d4e8834b7390f1ee6e6426cf318f221d8051 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Micha=C5=82=20Kope=C4=87?= Date: Thu, 3 Apr 2025 12:22:32 +0200 Subject: [PATCH 1/2] docs/kb/laptop-power-limit.md: add doc MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Signed-off-by: Michał Kopeć --- docs/kb/laptop-power-limit.md | 36 +++++++++++++++++++++++++++++++++++ mkdocs.yml | 1 + 2 files changed, 37 insertions(+) create mode 100644 docs/kb/laptop-power-limit.md diff --git a/docs/kb/laptop-power-limit.md b/docs/kb/laptop-power-limit.md new file mode 100644 index 00000000000..e506e30aeef --- /dev/null +++ b/docs/kb/laptop-power-limit.md @@ -0,0 +1,36 @@ +# Laptop power limits + +This article describes how power limiting works on Dasharo firmware for laptops. + +## Power sources + +A laptop may be powered from AC, or from battery. Each of these two has a limit +on how much power it can provide. + +- AC barrel jack: Depends on the wattage of the included power supply +- USB-PD: Depends on the wattage rating of the specific power supply being used, + and on the contract that was negotiated between the laptop and power supply +- Battery: Depends on the maximum discharge rate specified by the manufacturer + and on charge level + +The embedded controller must observe what sources of power are present and +adjust platform power limits accordingly. + +To limit power, the CPU is throttled using the Psys power limit mechanism. This +ensures that the power draw does not exceed the limit, by proactively throttling +CPU performance. + +## AC power limit + +This limit is a minimum of: + +- Power supply wattage x estimated power conversion efficiency +- Maximum current rating of the input power rail +- Wattage of the included AC power supply + +## DC power limit + +This power limit is a minimum of: + +- Battery capacity x 1C discharge rate +- Maximum current rating of the battery power rail diff --git a/mkdocs.yml b/mkdocs.yml index bf84368d46a..f50ddd6070a 100644 --- a/mkdocs.yml +++ b/mkdocs.yml @@ -461,6 +461,7 @@ nav: - 'Capsule Update Configs': kb/capsule-updates-configs.md - 'PCR Measurements': kb/pcr-measurements.md - 'NovaCustom dev setup': kb/laptop-dev-env.md + - 'Laptop power limits': kb/laptop-power-limit.md # - 'Trolling Topics List': # - 'Introduction': osf-trolling-list/osf_issues_taxonomy.md - 'FAQ': From 2a26f0c2f8e04a42c0ea51b8347d8fa2a5fdcc66 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Micha=C5=82=20Kope=C4=87?= Date: Wed, 16 Apr 2025 14:09:26 +0200 Subject: [PATCH 2/2] docs/kb/laptop-power-limit.md: capitalize EC MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Signed-off-by: Michał Kopeć --- docs/kb/laptop-power-limit.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/docs/kb/laptop-power-limit.md b/docs/kb/laptop-power-limit.md index e506e30aeef..77d35e8d335 100644 --- a/docs/kb/laptop-power-limit.md +++ b/docs/kb/laptop-power-limit.md @@ -13,7 +13,7 @@ on how much power it can provide. - Battery: Depends on the maximum discharge rate specified by the manufacturer and on charge level -The embedded controller must observe what sources of power are present and +The Embedded Controller must observe what sources of power are present and adjust platform power limits accordingly. To limit power, the CPU is throttled using the Psys power limit mechanism. This