linux-kernel - Re: [PATCH] arm64: dts: mediatek: mt8192: Fix CPUs capacity-dmips-mhz

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Message-ID: <01c88a42-274c-f8cf-73a6-29741579d9db@collabora.com>
Date:   Mon, 5 Jun 2023 10:21:54 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Nícolas F. R. A. Prado 
        <nfraprado@...labora.com>,
        Matthias Brugger <matthias.bgg@...il.com>
Cc:     kernel@...labora.com, Conor Dooley <conor+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Seiya Wang <seiya.wang@...iatek.com>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH] arm64: dts: mediatek: mt8192: Fix CPUs capacity-dmips-mhz

Il 02/06/23 20:35, Nícolas F. R. A. Prado ha scritto:
> The capacity-dmips-mhz parameter was miscalculated: this SoC runs
> the first (Cortex-A55) cluster at a maximum of 2000MHz and the
> second (Cortex-A76) cluster at a maximum of 2200MHz.
> 
> In order to calculate the right capacity-dmips-mhz, the following
> test was performed:
> 1. CPUFREQ governor was set to 'performance' on both clusters
> 2. Ran dhrystone with 500000000 iterations for 10 times on each cluster
> 3. Calculated the mean result for each cluster
> 4. Calculated DMIPS/MHz: dmips_mhz = dmips_per_second / cpu_mhz
> 5. Scaled results to 1024:
>     result_c0 = dmips_mhz_c0 / dmips_mhz_c1 * 1024
> 
> The mean results for this SoC are:
> Cluster 0 (LITTLE): 12016411 Dhry/s
> Cluster 1 (BIG): 31702034 Dhry/s
> 
> The calculated scaled results are:
> Cluster 0: 426.953226899238 (rounded to 427)
> Cluster 1: 1024
> 
> Fixes: 48489980e27e ("arm64: dts: Add Mediatek SoC MT8192 and evaluation board dts and Makefile")
> Signed-off-by: Nícolas F. R. A. Prado <nfraprado@...labora.com>
> 

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>