linux-kernel - Re: [PATCH v4 2/2] cpufreq: tegra124: Allow building as a module

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Message-ID: <4a9fe001-9104-4a11-986d-02651738d84d@nvidia.com>
Date: Thu, 15 May 2025 07:21:54 +0100
From: Jon Hunter <jonathanh@...dia.com>
To: Aaron Kling <webgeek1234@...il.com>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>,
 Viresh Kumar <viresh.kumar@...aro.org>,
 Thierry Reding <thierry.reding@...il.com>, linux-pm@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-tegra@...r.kernel.org
Subject: Re: [PATCH v4 2/2] cpufreq: tegra124: Allow building as a module


On 14/05/2025 17:30, Aaron Kling wrote:
> On Wed, May 14, 2025 at 5:32 AM Jon Hunter <jonathanh@...dia.com> wrote:
>>
>>
>> On 09/05/2025 01:04, Aaron Kling via B4 Relay wrote:
>>> From: Aaron Kling <webgeek1234@...il.com>
>>>
>>> This requires three changes:
>>> * A soft dependency on cpufreq-dt as this driver only handles power
>>>     management and cpufreq-dt does the real operations
>>> * Adding a remove routine to remove the cpufreq-dt device
>>> * Adding a exit routine to handle cleaning up the driver
>>>
>>> Signed-off-by: Aaron Kling <webgeek1234@...il.com>
>>> ---
>>>    drivers/cpufreq/Kconfig.arm        |  2 +-
>>>    drivers/cpufreq/tegra124-cpufreq.c | 36 ++++++++++++++++++++++++++++++++----
>>>    2 files changed, 33 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
>>> index 4f9cb943d945c244eb2b29f543d14df6cac4e5d4..625f6fbdaaf5fd774e3b0bb996eb7ce980da41ee 100644
>>> --- a/drivers/cpufreq/Kconfig.arm
>>> +++ b/drivers/cpufreq/Kconfig.arm
>>> @@ -238,7 +238,7 @@ config ARM_TEGRA20_CPUFREQ
>>>          This adds the CPUFreq driver support for Tegra20/30 SOCs.
>>>
>>>    config ARM_TEGRA124_CPUFREQ
>>> -     bool "Tegra124 CPUFreq support"
>>> +     tristate "Tegra124 CPUFreq support"
>>>        depends on ARCH_TEGRA || COMPILE_TEST
>>>        depends on CPUFREQ_DT
>>>        default y
>>> diff --git a/drivers/cpufreq/tegra124-cpufreq.c b/drivers/cpufreq/tegra124-cpufreq.c
>>> index bc0691e8971f9454def37f489e4a3e244100b9f4..b6059c91f2474c56809c403eca94eacf51df734f 100644
>>> --- a/drivers/cpufreq/tegra124-cpufreq.c
>>> +++ b/drivers/cpufreq/tegra124-cpufreq.c
>>> @@ -16,6 +16,8 @@
>>>    #include <linux/pm_opp.h>
>>>    #include <linux/types.h>
>>>
>>> +static struct platform_device *platform_device;
>>> +
>>>    struct tegra124_cpufreq_priv {
>>>        struct clk *cpu_clk;
>>>        struct clk *pllp_clk;
>>> @@ -176,6 +178,21 @@ static int __maybe_unused tegra124_cpufreq_resume(struct device *dev)
>>>        return err;
>>>    }
>>>
>>> +static void tegra124_cpufreq_remove(struct platform_device *pdev)
>>> +{
>>> +     struct tegra124_cpufreq_priv *priv = dev_get_drvdata(&pdev->dev);
>>> +
>>> +     if (!IS_ERR(priv->cpufreq_dt_pdev)) {
>>> +             platform_device_unregister(priv->cpufreq_dt_pdev);
>>> +             priv->cpufreq_dt_pdev = ERR_PTR(-ENODEV);
>>> +     }
>>> +
>>> +     clk_put(priv->pllp_clk);
>>> +     clk_put(priv->pllx_clk);
>>> +     clk_put(priv->dfll_clk);
>>> +     clk_put(priv->cpu_clk);
>>
>>
>> If we use devm_clk_get() in probe, then we should be able to avoid this.
> 
> I can do that. There's a lot of other cleanup like this that the
> driver could use based on newer kernel apis, but that's out of scope
> of this series.

I don't think that using devm_clk_get() is out the scope here, because 
this would greatly simplify the remove.

Jon

-- 
nvpublic