linux-kernel - Re: [PATCH v6 3/4] ALSA: cs35l41: Add shared boost feature

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Message-ID: <689ffdac-8d52-a76d-8a01-a43b8a7d9fa8@opensource.cirrus.com>
Date:   Wed, 22 Feb 2023 15:56:36 -0600
From:   David Rhodes <drhodes@...nsource.cirrus.com>
To:     Lucas Tanure <lucas.tanure@...labora.com>,
        David Rhodes <david.rhodes@...rus.com>,
        Charles Keepax <ckeepax@...nsource.cirrus.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Mark Brown <broonie@...nel.org>,
        "Rob Herring" <robh+dt@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>
CC:     <alsa-devel@...a-project.org>, <devicetree@...r.kernel.org>,
        <patches@...nsource.cirrus.com>, <linux-kernel@...r.kernel.org>,
        <kernel@...labora.com>
Subject: Re: [PATCH v6 3/4] ALSA: cs35l41: Add shared boost feature

On 2/22/23 03:32, Lucas Tanure wrote:
> +static const struct reg_sequence cs35l41_actv_seq[] = {
> +	/* SYNC_BST_CTL_RX_EN = 1; SYNC_BST_CTL_TX_EN = 1 */
> +	{CS35L41_MDSYNC_EN,        0x00003000},
> +	/* BST_CTL_SEL = MDSYNC */
> +	{CS35L41_BSTCVRT_VCTRL2,    0x00000002},
> +};
> +
> +static const struct reg_sequence cs35l41_pass_seq[] = {
> +	/* SYNC_BST_CTL_RX_EN = 1; SYNC_BST_CTL_TX_EN = 0 */
> +	{CS35L41_MDSYNC_EN,        0x00002000},
> +	/* BST_EN = 0 */
> +	{CS35L41_PWR_CTRL2,        0x00003300},
> +	/* BST_CTL_SEL = MDSYNC */
> +	{CS35L41_BSTCVRT_VCTRL2,    0x00000002},
> +};
> +

The passive device only needs to use TX, not RX.
It is transmitting its boost target voltage to the bus so that the
active amp can boost according to the combined target.

Should be:
static const struct reg_sequence cs35l41_pass_seq[] = {
	/* SYNC_BST_CTL_RX_EN = 0; SYNC_BST_CTL_TX_EN = 1 */
	{CS35L41_MDSYNC_EN,        0x00001000},
...

Thanks,
David