linux-kernel - Re: [PATCH 13/13] ALSA: hda/cs35l56: Add driver for Cirrus Logic CS35L56 amplifier

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Message-ID: <7c5f776d-bf17-ea3d-a4ee-3ac54194a215@opensource.cirrus.com>
Date:   Fri, 26 May 2023 13:20:32 +0100
From:   Richard Fitzgerald <rf@...nsource.cirrus.com>
To:     <Claudiu.Beznea@...rochip.com>, <tiwai@...e.com>,
        <broonie@...nel.org>, <perex@...ex.cz>
CC:     <alsa-devel@...a-project.org>, <linux-kernel@...r.kernel.org>,
        <patches@...nsource.cirrus.com>, <simont@...nsource.cirrus.com>
Subject: Re: [PATCH 13/13] ALSA: hda/cs35l56: Add driver for Cirrus Logic
 CS35L56 amplifier

On 26/5/23 05:40, Claudiu.Beznea@...rochip.com wrote:
> On 25.05.2023 18:06, Richard Fitzgerald wrote:
>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>>
>> From: Simon Trimmer <simont@...nsource.cirrus.com>
>>
>> Add a driver for the Cirrus Logic CS35L56 amplifier. This uses the same
>> component binding API as the CS35L41 driver. This is not a standalone
>> HDA device; it provides control of the CS35L56 for systems that use a
>> combination of an HDA codec and CS35L56 amplifiers with audio routed
>> through the HDA codec.
>>

<SNIP>

>> +
>> +       cs35l56->base.reset_gpio = devm_gpiod_get_index_optional(cs35l56->base.dev,
>> +                                                                "reset",
>> +                                                                cs35l56->index,
>> +                                                                GPIOD_OUT_LOW);
>> +       if (IS_ERR(cs35l56->base.reset_gpio)) {
> 
> devm_gpiod_get_index_optional() can also return NULL.
> 

Yes, that is expected. It's optional. It's not an error.
In that case cs35l56->base.reset_gpio will already be NULL.

>> +               ret = PTR_ERR(cs35l56->base.reset_gpio);
>> +
>> +               /*
>> +                * If RESET is shared the first amp to probe will grab the reset
>> +                * line and reset all the amps
>> +                */
>> +               if (ret != -EBUSY)
>> +                       return dev_err_probe(cs35l56->base.dev, ret, "Failed to get reset GPIO\n");
>> +
>> +               dev_info(cs35l56->base.dev, "Reset GPIO busy, assume shared reset\n");
>> +               cs35l56->base.reset_gpio = NULL;
>> +       }
>> +
>> +       return 0;
>> +
>> +err:
>> +       dev_err(cs35l56->base.dev, "Failed property %s: %d\n", property, ret);
>> +
>> +       return ret;
>> +}