linux-kernel - Re: [PATCH v3 4/8] ASoC: samsung: midas_wm1811: Add GPIO-based headset jack detection

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Message-ID: <2c4c0aeb-2870-4905-bcfc-642ae40c87f1@sirena.org.uk>
Date: Mon, 20 May 2024 15:41:17 +0100
From: Mark Brown <broonie@...nel.org>
To: Artur Weber <aweber.kernel@...il.com>
Cc: Sylwester Nawrocki <s.nawrocki@...sung.com>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Liam Girdwood <lgirdwood@...il.com>, Rob Herring <robh@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>,
	Alim Akhtar <alim.akhtar@...sung.com>, alsa-devel@...a-project.org,
	linux-sound@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org,
	~postmarketos/upstreaming@...ts.sr.ht
Subject: Re: [PATCH v3 4/8] ASoC: samsung: midas_wm1811: Add GPIO-based
 headset jack detection

On Sun, May 19, 2024 at 10:17:50AM +0200, Artur Weber wrote:

> +	if (priv->reg_headset_mic_bias) {
> +		/*
> +		 * Get state of Headset Mic switch by checking the headset mic
> +		 * bias regulator
> +		 */
> +		bias_already_on = \
> +			regulator_is_enabled(priv->reg_headset_mic_bias);

If you're going to do this you need to use regulator_get_exclusive() to
ensure that nothing else can enable the regulator, otherwise you should
just unconditionally enable the regulator.

> +	/*
> +	 * Revert the headset mic bias supply to its previous state
> +	 * (i.e. if it was disabled before the check, disable it again)
> +	 */
> +	if (priv->reg_headset_mic_bias && bias_already_on == 0) {
> +		ret = regulator_disable(priv->reg_headset_mic_bias);
> +		if (ret)
> +			pr_err("%s: Failed to disable micbias: %d\n",
> +			       __func__, ret);
> +	}

Given that you're just briefly bouncing the regulator on and off it'd be
best to just unconditionally enable and disable here, I can't see what
the enable check gains you other than possible race conditions.

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