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

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Message-ID: <f28470ca-93dc-cdf9-b008-54c7b50cfd83@samsung.com>
Date:   Tue, 16 Jul 2019 20:50:08 +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. 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.

> +		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.

> +
>  		err = dev_pm_opp_add(&pdev->dev, rate, 0);
>  		if (err) {
>  			dev_err(&pdev->dev, "Failed to add OPP: %d\n", err);
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics