linux-kernel - Re: [PATCH v4 03/24] PM / devfreq: tegra30: Handle possible round-rate error

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Date:   Tue, 16 Jul 2019 16:09:22 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Chanwoo Choi <cw00.choi@...sung.com>,
        Thierry Reding <thierry.reding@...il.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>
Cc:     linux-pm@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 03/24] PM / devfreq: tegra30: Handle possible
 round-rate error

16.07.2019 14:50, Chanwoo Choi пишет:
> On 19. 7. 8. 오전 7:32, Dmitry Osipenko wrote:
>> The EMC clock rate rounding technically could fail, hence let's handle
>> the error cases properly.
>>
>> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
>> ---
>>  drivers/devfreq/tegra30-devfreq.c | 17 +++++++++++++++--
>>  1 file changed, 15 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
>> index 5e2b133babdd..5e606ae3f238 100644
>> --- a/drivers/devfreq/tegra30-devfreq.c
>> +++ b/drivers/devfreq/tegra30-devfreq.c
>> @@ -592,8 +592,8 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
>>  	struct tegra_devfreq_device *dev;
>>  	struct tegra_devfreq *tegra;
>>  	struct devfreq *devfreq;
>> -	unsigned long rate;
>>  	unsigned int i;
>> +	long rate;
>>  	int err;
>>  
>>  	tegra = devm_kzalloc(&pdev->dev, sizeof(*tegra), GFP_KERNEL);
>> @@ -650,8 +650,14 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
>>  
>>  	reset_control_deassert(tegra->reset);
>>  
>> -	tegra->max_freq = clk_round_rate(tegra->emc_clock, ULONG_MAX) / KHZ;
>> +	rate = clk_round_rate(tegra->emc_clock, ULONG_MAX);
>> +	if (rate < 0) {
>> +		dev_err(&pdev->dev, "Failed to round clock rate: %ld\n", rate);
>> +		return rate;
>> +	}
>> +
>>  	tegra->cur_freq = clk_get_rate(tegra->emc_clock) / KHZ;
>> +	tegra->max_freq = rate / KHZ;
>>  
>>  	for (i = 0; i < ARRAY_SIZE(actmon_device_configs); i++) {
>>  		dev = tegra->devices + i;
>> @@ -662,6 +668,13 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
>>  	for (rate = 0; rate <= tegra->max_freq * KHZ; rate++) {
>>  		rate = clk_round_rate(tegra->emc_clock, rate);
>>  
> 
> Please remove unneeded blank line.

I can remove it, but it was added specifically to ease reading of the code.

>> +		if (rate < 0) {
>> +			dev_err(&pdev->dev,
>> +				"Failed to round clock rate: %ld\n", rate);
>> +			err = rate;
>> +			goto remove_opps;
>> +		}
> 
> Also, this patch doesn't contain code which restore the previous
> tegra->cur_freq/max_freq when error happen.

The error here results in abortion of the driver's probing, hence
nothing need to be restored in that case because nothing was changed at
this point yet.