linux-kernel - [PATCH 2/2] soc: samsung: exynos-asv: Update Energy Model after adjusting voltage

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Message-Id: <20231220110339.1065505-3-lukasz.luba@arm.com>
Date: Wed, 20 Dec 2023 11:03:39 +0000
From: Lukasz Luba <lukasz.luba@....com>
To: linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org
Cc: lukasz.luba@....com,
	dietmar.eggemann@....com,
	linux-arm-kernel@...ts.infradead.org,
	sboyd@...nel.org,
	nm@...com,
	linux-samsung-soc@...r.kernel.org,
	daniel.lezcano@...aro.org,
	rafael@...nel.org,
	viresh.kumar@...aro.org,
	krzysztof.kozlowski@...aro.org,
	alim.akhtar@...sung.com,
	m.szyprowski@...sung.com,
	xuewen.yan94@...il.com,
	mhiramat@...nel.org,
	qyousef@...alina.io,
	wvw@...gle.com
Subject: [PATCH 2/2] soc: samsung: exynos-asv: Update Energy Model after adjusting voltage

When the voltage for OPPs is adjusted there is a need to also update
Energy Model framework. The EM data contains power values which depend
on voltage values. The EM structure is used for thermal (IPA governor)
and in scheduler task placement (EAS) so it should reflect the real HW
model as best as possible to operate properly.

Based on data on Exynos5422 ASV tables the maximum power difference might
be ~29%. An Odroid-XU4 (with a random sample SoC in this chip lottery)
showed power difference for some OPPs ~20%. Therefore, it's worth to
update the EM.

Signed-off-by: Lukasz Luba <lukasz.luba@....com>
---
 drivers/soc/samsung/exynos-asv.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/soc/samsung/exynos-asv.c b/drivers/soc/samsung/exynos-asv.c
index d60af8acc391..328f079423d6 100644
--- a/drivers/soc/samsung/exynos-asv.c
+++ b/drivers/soc/samsung/exynos-asv.c
@@ -97,9 +97,17 @@ static int exynos_asv_update_opps(struct exynos_asv *asv)
 			last_opp_table = opp_table;
 
 			ret = exynos_asv_update_cpu_opps(asv, cpu);
-			if (ret < 0)
+			if (!ret) {
+				/*
+				 * When the voltage for OPPs successfully
+				 * changed, update the EM power values to
+				 * reflect the reality and not use stale data
+				 */
+				dev_pm_opp_of_update_em(cpu);
+			} else {
 				dev_err(asv->dev, "Couldn't udate OPPs for cpu%d\n",
 					cpuid);
+			}
 		}
 
 		dev_pm_opp_put_opp_table(opp_table);
-- 
2.25.1