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

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Message-ID: <faf0f014-71e6-ace9-391f-8b0080d94dc6@samsung.com>
Date:   Wed, 17 Jul 2019 15:38:46 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Dmitry Osipenko <digetx@...il.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

On 19. 7. 16. 오후 10:09, Dmitry Osipenko wrote:
> 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.
> 
> 

OK.


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics