linux-kernel - Re: [PATCH v2 2/3] ASoC: starfive: Add JH7110 PWM-DAC driver

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Message-ID: <34c8c9d5-fad0-52ce-d1e6-798546005bfd@starfivetech.com>
Date:   Thu, 3 Aug 2023 16:37:50 +0800
From:   Hal Feng <hal.feng@...rfivetech.com>
To:     Mark Brown <broonie@...nel.org>
CC:     Liam Girdwood <lgirdwood@...il.com>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Claudiu Beznea <claudiu.beznea@...rochip.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Walker Chen <walker.chen@...rfivetech.com>,
        Xingyu Wu <xingyu.wu@...rfivetech.com>,
        Emil Renner Berthing <emil.renner.berthing@...onical.com>,
        <alsa-devel@...a-project.org>, <devicetree@...r.kernel.org>,
        <linux-riscv@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/3] ASoC: starfive: Add JH7110 PWM-DAC driver

On Mon, 31 Jul 2023 20:14:38 +0100, Mark Brown wrote:
> On Mon, Jul 31, 2023 at 11:28:28AM +0800, Hal Feng wrote:
> 
>> +static const struct jh7110_ct_pwmdac pwmdac_ct_data_shift[] = {
>> +	{ .name = "left 0 bit", .vals = PWMDAC_DATA_LEFT_SHIFT_BIT_0 },
>> +	{ .name = "left 1 bit", .vals = PWMDAC_DATA_LEFT_SHIFT_BIT_1 },
>> +	{ .name = "left 2 bit", .vals = PWMDAC_DATA_LEFT_SHIFT_BIT_2 },
>> +	{ .name = "left 3 bit", .vals = PWMDAC_DATA_LEFT_SHIFT_BIT_3 },
>> +	{ .name = "left 4 bit", .vals = PWMDAC_DATA_LEFT_SHIFT_BIT_4 },
>> +	{ .name = "left 5 bit", .vals = PWMDAC_DATA_LEFT_SHIFT_BIT_5 },
>> +	{ .name = "left 6 bit", .vals = PWMDAC_DATA_LEFT_SHIFT_BIT_6 },
>> +	{ .name = "left 7 bit", .vals = PWMDAC_DATA_LEFT_SHIFT_BIT_7 }
>> +};
> 
> It's not clear to me why this is user selectable - what does the control
> do?

It's convenient to change the register values in user space with the
control. But actually using fixed register configuration is enough.
I will drop all these control in the next version.

> 
>> +static int jh7110_pwmdac_put(struct snd_kcontrol *kcontrol,
>> +			     struct snd_ctl_elem_value *ucontrol,
>> +			     int pwmdac_ct)
>> +{
>> +	struct snd_soc_component *component = snd_kcontrol_chip(kcontrol);
>> +	struct jh7110_pwmdac_dev *dev = snd_soc_component_get_drvdata(component);
>> +	int sel = ucontrol->value.enumerated.item[0];
>> +	unsigned int items;
> 
>> +	if (pwmdac_ct == PWMDAC_CT_SHIFT)
>> +		dev->shift = pwmdac_ct_shift[sel].vals;
>> +	else if (pwmdac_ct == PWMDAC_CT_DUTY_CYCLE)
>> +		dev->duty_cycle = pwmdac_ct_duty_cycle[sel].vals;
>> +	else if (pwmdac_ct == PWMDAC_CT_DATA_CHANGE)
>> +		dev->data_change = pwmdac_ct_data_change[sel].vals;
>> +	else if (pwmdac_ct == PWMDAC_CT_DATA_MODE)
>> +		dev->data_mode = pwmdac_ct_data_mode[sel].vals;
>> +	else if (pwmdac_ct == PWMDAC_CT_DATA_SHIFT)
>> +		dev->data_shift = pwmdac_ct_data_shift[sel].vals;
>> +
>> +	return 0;
>> +}
> 
> _put() operations should return 1 if the control value changes so event
> generation works - please test a card using this driver with the
> mixer-test selftest, it'll identify this and a bunch of other potential
> issues.

Thanks for the correct, but it doesn't matter as I will drop these control
later.

> 
>> +static int jh7110_pwmdac_component_probe(struct snd_soc_component *component)
>> +{
>> +	snd_soc_add_component_controls(component, jh7110_pwmdac_snd_controls,
>> +				       ARRAY_SIZE(jh7110_pwmdac_snd_controls));
>> +	return 0;
>> +}
> 
> The driver can just point to the controls from the _driver struct and
> skip having a probe() function.

Thanks for your advice, but I would like to drop these control later.

Thanks again for your review.

Best regards,
Hal