ASoC: atmel: atmel-classd: Re-add dai_link->platform to fix card init

The removed dai_link->platform component cause a fail which is exposed at runtime. (ex: when a sound tool is used) This patch re-adds the dai_link->platform component to have a full card registered.

Before this patch:

:~$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: CLASSD [CLASSD], device 0: CLASSD PCM snd-soc-dummy-dai-0 []
    Subdevices: 1/1
    Subdevice #0: subdevice #0

:~$ speaker-test -t sine
speaker-test 1.2.6
Playback device is default
Stream parameters are 48000Hz, S16_LE, 1 channels
Sine wave rate is 440.0000Hz
Playback open error: -22,Invalid argument

After this patch which restores the platform component:

:~$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: CLASSD [CLASSD], device 0: CLASSD PCM snd-soc-dummy-dai-0
						[CLASSD PCM snd-soc-dummy-dai-0]
    Subdevices: 1/1
    Subdevice #0: subdevice #0
-> Resolve the playback error.

---
 sound/soc/atmel/atmel-classd.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

index 6aed1ee443b4..ba314b279919 100644
@@ -473,19 +473,22 @@ static int atmel_classd_asoc_card_init(struct device *dev,
 	if (!dai_link)
 		return -ENOMEM;
 
-	comp = devm_kzalloc(dev, sizeof(*comp), GFP_KERNEL);
+	comp = devm_kzalloc(dev, 2 * sizeof(*comp), GFP_KERNEL);
 	if (!comp)
 		return -ENOMEM;
 
-	dai_link->cpus		= comp;
+	dai_link->cpus		= &comp[0];
 	dai_link->codecs	= &snd_soc_dummy_dlc;
+	dai_link->platforms	= &comp[1];
 
 	dai_link->num_cpus	= 1;
 	dai_link->num_codecs	= 1;
+	dai_link->num_platforms = 1;
 
 	dai_link->name			= "CLASSD";
 	dai_link->stream_name		= "CLASSD PCM";
 	dai_link->cpus->dai_name	= dev_name(dev);
+	dai_link->platforms->name	= dev_name(dev);
 
 	card->dai_link	= dai_link;
 	card->num_links	= 1;

2.34.1

Hi Andrei

Thank you for the patch, and sorry to bother you by my patch.

I would like to ask for reference. What is this "sound tool" ? (Is it on userland side ? or Kernel side ?)
And do you know what it will do to dai_link->platform ?

Thank you for your help !!
Best regards
---
Kuninori Morimoto

Hi Kuninori,

It is on userland side like : arecord, aplay - command-line sound recorder and player for ALSA soundcard driver or speaker-test - command-line speaker test tone generator for ALSA

A platform driver is critical for interfacing between userland audio applications and the physical audio hardware. Proper implementation ensures successful audio playback and recording.

On the basic level of how it works when a userland application plays audio:
1. The ALSA subsystem processes the audio stream and sends it to the appropriate driver through the ASoC layer.
2. The dai_link->platform component is responsible for managing the data transfer, using DMA, to the codec (Class D amplifier).
3. The codec driver then converts the digital audio data into a PWM signal or other suitable digital representation that directly drives the loudspeaker.

Best regards,
Andrei Simion

Applied to

https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-next

Thanks!

[1/1] ASoC: atmel: atmel-classd: Re-add dai_link->platform to fix card init

      commit: 2ed22161b19b11239aa742804549f63edd7c91e3

All being well this means that it will be integrated into the linux-next tree (usually sometime in the next 24 hours) and sent to Linus during the next merge window (or sooner if it is a bug fix), however if problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing and review of the tree, please engage with people reporting problems and send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they should be sent as incremental updates against current git, existing patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying to this mail.

Thanks,
Mark