linux-kernel - Re: [PATCH v1] cpufreq: tegra20: Fix imbalanced clock enable count

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Message-ID: <68f62691-9108-9bee-a24d-5c978af8a5ab@gmail.com>
Date:   Wed, 23 May 2018 13:44:18 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        linux-tegra@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] cpufreq: tegra20: Fix imbalanced clock enable count

On 23.05.2018 08:58, Viresh Kumar wrote:
> On 23-05-18, 00:14, Dmitry Osipenko wrote:
>> Tegra20-cpufreq driver missed enabling the CPU clocks. This results in a
>> clock-enable refcount disbalance on PLL_P <-> PLL_X reparent, causing
>> PLL_X to get disabled while it shouldn't. Fix this by enabling the clocks
>> on the driver probe.
>>
>> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
>> ---
>>
>> CPUFreq maintainers,
>>
>> Please take into account that this patch is made on top of my recent
>> series of patches [0] "Clean up Tegra20 cpufreq driver" that was fully
>> reviewed, but seems not applied yet. Let me know if you prefer to re-spin
>> the [0], including this patch into the series.
>>
>> [0] https://patchwork.ozlabs.org/project/linux-tegra/list/?series=45321
> 
> This is already picked by Rafael and is sitting in pm/bleeding-edge
> branch. Should get merged into linux-next in a day or two.
> 
>>  drivers/cpufreq/tegra20-cpufreq.c | 16 +++++++++++++++-
>>  1 file changed, 15 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/cpufreq/tegra20-cpufreq.c b/drivers/cpufreq/tegra20-cpufreq.c
>> index 05f57dcd5215..ca5229265b60 100644
>> --- a/drivers/cpufreq/tegra20-cpufreq.c
>> +++ b/drivers/cpufreq/tegra20-cpufreq.c
>> @@ -176,6 +176,14 @@ static int tegra20_cpufreq_probe(struct platform_device *pdev)
>>  		goto put_pll_x;
>>  	}
>>  
>> +	err = clk_prepare_enable(cpufreq->pll_x_clk);
>> +	if (err)
>> +		goto put_pll_p;
>> +
>> +	err = clk_prepare_enable(cpufreq->pll_p_clk);
>> +	if (err)
>> +		goto disable_pll_x;
>> +
>>  	cpufreq->dev = &pdev->dev;
>>  	cpufreq->driver.get = cpufreq_generic_get;
>>  	cpufreq->driver.attr = cpufreq_generic_attr;
>> @@ -192,12 +200,16 @@ static int tegra20_cpufreq_probe(struct platform_device *pdev)
>>  
>>  	err = cpufreq_register_driver(&cpufreq->driver);
>>  	if (err)
>> -		goto put_pll_p;
>> +		goto disable_pll_p;
>>  
>>  	platform_set_drvdata(pdev, cpufreq);
>>  
>>  	return 0;
>>  
>> +disable_pll_p:
>> +	clk_disable_unprepare(cpufreq->pll_p_clk);
>> +disable_pll_x:
>> +	clk_disable_unprepare(cpufreq->pll_x_clk);
>>  put_pll_p:
>>  	clk_put(cpufreq->pll_p_clk);
>>  put_pll_x:
>> @@ -214,6 +226,8 @@ static int tegra20_cpufreq_remove(struct platform_device *pdev)
>>  
>>  	cpufreq_unregister_driver(&cpufreq->driver);
>>  
>> +	clk_disable_unprepare(cpufreq->pll_p_clk);
>> +	clk_disable_unprepare(cpufreq->pll_x_clk);
>>  	clk_put(cpufreq->pll_p_clk);
>>  	clk_put(cpufreq->pll_x_clk);
>>  	clk_put(cpufreq->cpu_clk);
> 
> Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
> 

Please hold on this patch, seems I interpreted the cpufreq driver logic
incorrectly and it is probably fine as it is. I'll re-check later today.