linux-kernel - Re: [PATCH 4/4] ALSA: hda/cirrus: Add Headphone and Headset MIC Volume Control

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Date:   Thu, 04 Mar 2021 14:49:31 +0100
From:   Takashi Iwai <tiwai@...e.de>
To:     Vitaly Rodionov <vitalyr@...nsource.cirrus.com>
Cc:     Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>,
        <alsa-devel@...a-project.org>, <patches@...nsource.cirrus.com>,
        <linux-kernel@...r.kernel.org>,
        Stefan Binding <sbinding@...nsource.cirrus.com>
Subject: Re: [PATCH 4/4] ALSA: hda/cirrus: Add Headphone and Headset MIC Volume Control

On Wed, 03 Mar 2021 19:29:59 +0100,
Vitaly Rodionov wrote:
> 
> +static int cs8409_cs42l42_volume_get(struct snd_kcontrol *kcontrol,
> +				 struct snd_ctl_elem_value *ucontrol)
> +{
> +	struct hda_codec *codec = snd_kcontrol_chip(kcontrol);
> +	hda_nid_t nid = get_amp_nid(kcontrol);
> +	int chs = get_amp_channels(kcontrol);
> +	long *valp = ucontrol->value.integer.value;
> +	char vol = 0;
> +
> +	codec_dbg(codec, "%s() nid: %d\n", __func__, nid);
> +	snd_hda_power_up(codec);
> +	switch (nid) {
> +	case CS8409_CS42L42_HP_PIN_NID:
> +		mutex_lock(&cs8409_i2c_mux);
> +		if (chs & 1) {
> +			vol = -(cs8409_i2c_read(codec, CS42L42_I2C_ADDR,
> +				CS8409_CS42L42_REG_HS_VOLUME_CHA, 1));

Better to cache the values instead of i2c read at each time?
Then the unnecessary power up/down sequence can be avoided, too.


thanks,

Takashi