linux-kernel - Re: [Patch v2 7/9] cpufreq: tegra194: add OPP support and set bandwidth

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Date:   Thu, 23 Feb 2023 15:06:26 +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>, <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 v2 7/9] cpufreq: tegra194: add OPP support and set
 bandwidth



On 22/02/23 09:33, Viresh Kumar wrote:
> External email: Use caution opening links or attachments
> 
> 
> On 20-02-23, 19:35, Sumit Gupta wrote:
>> +static int tegra_cpufreq_set_bw(struct cpufreq_policy *policy, unsigned long freq_khz)
>> +{
>> +     struct dev_pm_opp *opp;
>> +     struct device *dev;
>> +     int ret;
>> +
>> +     dev = get_cpu_device(policy->cpu);
>> +     if (!dev)
>> +             return -ENODEV;
>> +
>> +     opp = dev_pm_opp_find_freq_exact(dev, freq_khz * KHZ, true);
>> +     if (IS_ERR(opp))
>> +             return PTR_ERR(opp);
>> +
>> +     ret = dev_pm_opp_set_opp(dev, opp);
>> +     dev_pm_opp_put(opp);
> 
> What about dev_pm_opp_set_rate() instead ?
> 
>> +     return ret;
>> +}
> 
> --
> viresh

Tried using it and got below crash. It seems to be coming because we 
don't have clocks property within CPU node for SoC's having BPMP-FW.

  Unable to handle kernel NULL pointer dereference at virtual address 
000000000000002e
  ....
  Call trace:
   clk_round_rate+0x38/0xd8
   dev_pm_opp_set_rate+0xe4/0x1a8
   tegra194_cpufreq_set_target+0x74/0x88
   __cpufreq_driver_target+0x154/0x250
   cpufreq_online+0x7b4/0x9ac

Thanks,
Sumit