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

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Date:   Tue, 18 Apr 2023 15:51:49 +0530
From:   Sumit Gupta <sumitg@...dia.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
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>, Sumit Gupta <sumitg@...dia.com>
Subject: Re: [Patch v6 6/9] cpufreq: tegra194: add OPP support and set
 bandwidth



On 18/04/23 14:43, Viresh Kumar wrote:
> External email: Use caution opening links or attachments
> 
> 
> 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

Yes, this can be applied independently.

Thank you,
Sumit Gupta