linux-kernel - Re: [Patch v6 6/9] cpufreq: tegra194: add OPP support and set bandwidth

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Message-ID: <20230418091315.bxh4hp6g3vekdi2r@vireshk-i7>
Date:   Tue, 18 Apr 2023 14:43:15 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Sumit Gupta <sumitg@...dia.com>
Cc:     treding@...dia.com, krzysztof.kozlowski@...aro.org,
        dmitry.osipenko@...labora.com, rafael@...nel.org,
        jonathanh@...dia.com, robh+dt@...nel.org, lpieralisi@...nel.org,
        helgaas@...nel.org, linux-kernel@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-pci@...r.kernel.org,
        mmaddireddy@...dia.com, kw@...ux.com, bhelgaas@...gle.com,
        vidyas@...dia.com, sanjayc@...dia.com, ksitaraman@...dia.com,
        ishah@...dia.com, bbasu@...dia.com
Subject: Re: [Patch v6 6/9] cpufreq: tegra194: add OPP support and set
 bandwidth

On 11-04-23, 16:29, Sumit Gupta wrote:
> Add support to use OPP table from DT in Tegra194 cpufreq driver.
> Tegra SoC's receive the frequency lookup table (LUT) from BPMP-FW.
> Cross check the OPP's present in DT against the LUT from BPMP-FW
> and enable only those DT OPP's which are present in LUT also.
> 
> The OPP table in DT has CPU Frequency to bandwidth mapping where
> the bandwidth value is per MC channel. DRAM bandwidth depends on the
> number of MC channels which can vary as per the boot configuration.
> This per channel bandwidth from OPP table will be later converted by
> MC driver to final bandwidth value by multiplying with number of
> channels before sending the request to BPMP-FW.
> 
> If OPP table is not present in DT, then use the LUT from BPMP-FW
> directy as the CPU frequency table and not do the DRAM frequency
> scaling which is same as the current behavior.
> 
> Now, as the CPU Frequency table is being controlling through OPP
> table in DT. Keeping fewer entries in the table will create less
> frequency steps and can help to scale fast to high frequencies
> when required.
> 
> Signed-off-by: Sumit Gupta <sumitg@...dia.com>
> ---
>  drivers/cpufreq/tegra194-cpufreq.c | 156 ++++++++++++++++++++++++++---
>  1 file changed, 143 insertions(+), 13 deletions(-)

Can this be applied independently of the rest of the series ?

-- 
viresh