linux-kernel - Re: [PATCH v1] PM / devfreq: tegra30: Improve initial hardware resetting

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Message-ID: <9cf563cc-fa74-4a98-c4e2-022dab675a9d@samsung.com>
Date:   Mon, 28 Sep 2020 12:20:59 +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>
Cc:     linux-pm@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] PM / devfreq: tegra30: Improve initial hardware
 resetting

On 9/28/20 5:51 AM, Dmitry Osipenko wrote:
> It's safe to enable the ACTMON clock at any time during driver probing,
> even if we don't know the state of hardware, because it's used only for
> collecting and processing stats, and interrupt is kept disabled. This
> allows us to slightly improve code which performs initial hardware
> resetting by making use of a single reset_control_reset() instead of
> assert/deassert pair. Secondly, a potential error of the reset-control
> API is handled nicely now.
> 
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
>  drivers/devfreq/tegra30-devfreq.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
> index dedd39de7367..f5e74c2ede85 100644
> --- a/drivers/devfreq/tegra30-devfreq.c
> +++ b/drivers/devfreq/tegra30-devfreq.c
> @@ -822,8 +822,6 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
>  		return err;
>  	}
>  
> -	reset_control_assert(tegra->reset);
> -
>  	err = clk_prepare_enable(tegra->clock);
>  	if (err) {
>  		dev_err(&pdev->dev,
> @@ -831,7 +829,11 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
>  		return err;
>  	}
>  
> -	reset_control_deassert(tegra->reset);
> +	err = reset_control_reset(tegra->reset);
> +	if (err) {
> +		dev_err(&pdev->dev, "Failed to reset hardware: %d\n", err);
> +		goto disable_clk;
> +	}
>  
>  	rate = clk_round_rate(tegra->emc_clock, ULONG_MAX);
>  	if (rate < 0) {
> 

Applied it. Thanks.

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics