linux-kernel - Re: [PATCH v2 1/3] rtc: tps6594: add driver for TPS6594 PMIC RTC

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Message-ID: <202303280929448e41808d@mail.local>
Date:   Tue, 28 Mar 2023 11:29:44 +0200
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     Esteban Blanc <eblanc@...libre.com>
Cc:     linus.walleij@...aro.org, lgirdwood@...il.com, broonie@...nel.org,
        a.zummo@...ertech.it, linux-kernel@...r.kernel.org,
        linux-gpio@...r.kernel.org, linux-rtc@...r.kernel.org,
        jpanis@...libre.com, jneanne@...libre.com, sterzik@...com,
        u-kumar1@...com
Subject: Re: [PATCH v2 1/3] rtc: tps6594: add driver for TPS6594 PMIC RTC

Hello,

On 28/03/2023 11:14:46+0200, Esteban Blanc wrote:
> +	/* Start rtc */
> +	ret = regmap_set_bits(tps->regmap, TPS6594_REG_RTC_CTRL_1,
> +			      TPS6594_BIT_STOP_RTC);
> +	if (ret < 0)
> +		return ret;
> +
> +	mdelay(100);
> +
> +	/*
> +	 * RTC should be running now. Check if this is the case.
> +	 * If not it might be a missing oscillator.
> +	 */
> +	ret = regmap_test_bits(tps->regmap, TPS6594_REG_RTC_STATUS,
> +			       TPS6594_BIT_RUN);
> +	if (ret < 0)
> +		return ret;
> +	if (ret == 0)
> +		return -ENODEV;
> +
> +	/* Stop RTC until first call to `tps6594_rtc_set_time */
> +	ret = regmap_clear_bits(tps->regmap, TPS6594_REG_RTC_CTRL_1,
> +				TPS6594_BIT_STOP_RTC);
> +	if (ret < 0)
> +		return ret;
> +

This whole block must not be executed when the RTC is already running,
else, you are stopping a perfectly running RTC.

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com