linux-kernel - Re: [PATCH v2 4/7] thermal: exynos: simplify regulator (de)initialization

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Message-ID: <bf9a07ff-5628-05ab-2362-a917d3d38313@linaro.org>
Date:   Wed, 13 Sep 2023 10:11:56 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Mateusz Majewski <m.majewski2@...sung.com>,
        linux-pm@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Bartlomiej Zolnierkiewicz <bzolnier@...il.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Amit Kucheria <amitk@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>
Subject: Re: [PATCH v2 4/7] thermal: exynos: simplify regulator
 (de)initialization

On 11/09/2023 15:34, Mateusz Majewski wrote:
> This does reduce the error granularity a bit, but the code
> simplification seems to be worth it.
> 
> Signed-off-by: Mateusz Majewski <m.majewski2@...sung.com>
> ---
>  drivers/thermal/samsung/exynos_tmu.c | 33 +++++++---------------------
>  1 file changed, 8 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/thermal/samsung/exynos_tmu.c b/drivers/thermal/samsung/exynos_tmu.c
> index ba9414b419ef..8451deb65f43 100644
> --- a/drivers/thermal/samsung/exynos_tmu.c
> +++ b/drivers/thermal/samsung/exynos_tmu.c
> @@ -157,7 +157,6 @@ enum soc_type {
>   * @reference_voltage: reference voltage of amplifier
>   *	in the positive-TC generator block
>   *	0 < reference_voltage <= 31
> - * @regulator: pointer to the TMU regulator structure.
>   * @tzd: pointer to thermal_zone_device structure
>   * @ntrip: number of supported trip points.
>   * @enabled: current status of TMU device
> @@ -183,7 +182,6 @@ struct exynos_tmu_data {
>  	u16 temp_error1, temp_error2;
>  	u8 gain;
>  	u8 reference_voltage;
> -	struct regulator *regulator;
>  	struct thermal_zone_device *tzd;
>  	unsigned int ntrip;
>  	bool enabled;
> @@ -994,42 +992,34 @@ static int exynos_tmu_probe(struct platform_device *pdev)
>  	 * TODO: Add regulator as an SOC feature, so that regulator enable
>  	 * is a compulsory call.
>  	 */
> -	data->regulator = devm_regulator_get_optional(&pdev->dev, "vtmu");
> -	if (!IS_ERR(data->regulator)) {
> -		ret = regulator_enable(data->regulator);
> -		if (ret) {
> -			dev_err(&pdev->dev, "failed to enable vtmu\n");
> -			return ret;
> -		}
> -	} else {
> -		if (PTR_ERR(data->regulator) == -EPROBE_DEFER)
> +	ret = devm_regulator_get_enable_optional(&pdev->dev, "vtmu");
> +	if (ret) {
> +		if (ret == -EPROBE_DEFER)
>  			return -EPROBE_DEFER;
> -		dev_info(&pdev->dev, "Regulator node (vtmu) not found\n");
> +		dev_info(&pdev->dev, "Failed to get regulator node (vtmu)\n");

This is not equivalent. If regulator is provided and enable fails, the
old code is nicely returning error. Now, it will print misleading
message - failed to get regulator - and continue.

While this simplifies the code, it ignores important running condition -
having regulator enabled.

Best regards,
Krzysztof