From mboxrd@z Thu Jan 1 00:00:00 1970 From: Leo Yan Subject: [PATCH v3 4/4] thermal: power_allocator: document k_pu_ratio/k_po_ratio Date: Wed, 6 Jan 2016 16:53:48 +0800 Message-ID: <1452070428-2567-5-git-send-email-leo.yan@linaro.org> References: <1452070428-2567-1-git-send-email-leo.yan@linaro.org> Return-path: In-Reply-To: <1452070428-2567-1-git-send-email-leo.yan@linaro.org> Sender: linux-kernel-owner@vger.kernel.org To: Jonathan Corbet , Zhang Rui , Eduardo Valentin , Javi Merino , Punit Agrawal , Daniel Kurtz , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, Daniel Thompson Cc: Leo Yan List-Id: linux-pm@vger.kernel.org Document k_pu_ratio and k_po_ratio's purpose, and refine formula to demonstrate to use ratio to calculate k_pu/k_po. Signed-off-by: Leo Yan --- Documentation/thermal/power_allocator.txt | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/Documentation/thermal/power_allocator.txt b/Documentation/thermal/power_allocator.txt index a1ce223..8958dab 100644 --- a/Documentation/thermal/power_allocator.txt +++ b/Documentation/thermal/power_allocator.txt @@ -114,13 +114,20 @@ whilst temperature is low, and may lead to temperature overshooting. The default value for `k_pu` is: - 2 * sustainable_power / (desired_temperature - switch_on_temp) + k_pu_ratio * sustainable_power / (desired_temperature - switch_on_temp) This means that at `switch_on_temp` the output of the controller's -proportional term will be 2 * `sustainable_power`. The default value -for `k_po` is: +proportional term will be k_pu_ratio * `sustainable_power`. - sustainable_power / (desired_temperature - switch_on_temp) +The default value for `k_po` is: + + k_po_ratio * sustainable_power / (desired_temperature - switch_on_temp) + +k_pu_ratio's default value is 2 and k_po_ratio's default value is 1. +These two vairants mean the ratio value compared against sustainable power, +so smaller ratio will result in thermal slower ramp. User can set these two +ratio value from sys filesystem nodes, finally k_pu and k_po will be +calculated by updated ratio value. Focusing on the proportional and feed forward values of the PID controller equation we have: -- 1.9.1