From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932428AbdJXK13 (ORCPT ); Tue, 24 Oct 2017 06:27:29 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:53120 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932306AbdJXK10 (ORCPT ); Tue, 24 Oct 2017 06:27:26 -0400 From: Dietmar Eggemann To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: Russell King , Vincent Guittot , Juri Lelli Subject: [PATCH v3 0/2] arm: remove cpu_efficiency Date: Tue, 24 Oct 2017 11:27:16 +0100 Message-Id: <20171024102718.16113-1-dietmar.eggemann@arm.com> X-Mailer: git-send-email 2.11.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org v2: review results [1]: Vincent pointed out that there are missing of_node_put() calls for cpu device node in parse_dt_topology(). Added them with an extra patch. v1: review results [2]: Vincent pointed out that there is a superfluous continue statement in parse_dt_topology(). Got rid of it. Krzysztof Kozlowski took the exynos and Simon Horman the renesas related dt bits into their for-next (v4.15) branches. *** For Cortex-A15/A7 arm big.LITTLE systems there are currently two ways to set the cpu capacity. The first one (commit 06073ee26775 "ARM: 8621/3: parse cpu capacity-dmips-mhz from DT") is based on dt 'cpu capacity-dmips-mhz' bindings and the appropriate dt parsing code in drivers/base/arch_topology.c. It further takes differences in maximum cpu frequency values into consideration, normalizes the maximum cpu capacity to SCHED_CAPACITY_SCALE (1024) and scales all the cpus accordingly. cpu capacity = (capacity-dmips-mhz * max cpu frequency) / (max capacity-dmips-mhz * max (max cpu frequency) This solution is shared between arm and arm64 and works for other combinations of big and little cpus (besides Cortex-A15/A7) as well. The second one (commit 339ca09d7ada "ARM: 7463/1: topology: Update cpu_power according to DT information" is based on the 'struct cpu_efficiency table_efficiency[]' and the dt parsing code in arch/arm/kernel/topology.c. It further requires a clock-frequency property per cpu node, calculates a so called middle frequency for an average cpu in the system which is as close as possible to SCHED_CAPACITY_SCALE (1024) and uses this to compute the cpu capacity values. cpu capacity = (cpu efficiency * clock frequency) / middle capacity This solution only works for Cortex-A15/A7 arm big.LITTLE systems. The aim of this patch is to have only one solution for all arm and arm64 big.LITTLE platforms. (1) Therefore, it removes the code for the 'cpu_efficiency/ clock-frequency dt property' (second) solution. (2) Moreover, it will also assure that the highest original cpu capacity (rq->cpu_capacity_orig) in a non-smt system is SCHED_CAPACITY_SCALE (1024). (3) And finally, another advantage is the dynamic detection of the max cpu frequency which comes with the first solution instead of the static clock-frequency dt property value. Currently, the arm dt parsing code in parse_dt_topology() checks if the dt uses the capacity-dmips-mhz property. If this is the case it uses the first, otherwise the second solution. This patch removes the code for the second solution from arch/arm/kernel/topology.c. With the dt related patches for exynos and renesas now in the appropriated for-next branches for v4.15 there are no Cortex-A15/A7 arm big.LITTLE systems left relying on the 'cpu_efficiency/clock-frequency dt property' based solution anymore. This patch has been tested on TC2 and Samsung Chromebook 2 13" (peach-pi, Exynos 5800). [1] https://marc.info/?l=linux-kernel&m=150781686132670&w=2 [2] https://marc.info/?l=linux-kernel&m=150410411807050&w=2 Changes v2->v3: - Rebase on top of v4.14-rc6 - Added missing of_node_put() for cpu device node [02/02] Changes v1->v2: - Rebase on top of v4.14-rc4 - Remove superfluous continue statement in parse_dt_topology() [01/04] - Remove 'cpu capacity scale management' and 'cpu capacity table' related comments [01/04] - Remove dt related patches [02-04/04] Dietmar Eggemann (2): arm: topology: remove cpu_efficiency arm: topology: add missing of_node_put() for cpu device node arch/arm/kernel/topology.c | 135 ++------------------------------------------- 1 file changed, 6 insertions(+), 129 deletions(-) -- 2.11.0