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-----Original Message----- From: Lars-Peter Clausen lars@metafoo.de Sent: Saturday, May 17, 2025 2:33 PM To: Steve Broshar steve@palmerwirelessmedtech.com; alsa-devel@alsa-project.org Subject: Re: Request for help: How to upgrade a sound driver from kernel 4.14 to 6.6

On 5/16/25 12:50, Steve Broshar wrote:

I have an audio driver/module that builds for kernel 4.14, but not for 6.6 due to changes in the kernel API.I find that API types (structs) and functions have been removed or changed, but IDK how to modify my code to use the updated API. Further, some of the changes seem less than clean. For example, in a couple places struct fields have been removed, but comments that used to precede the fields are still there such the comments are clearly no longer relevant and are therefore confusing. I have to wonder how many comments are out-of-date.

My ask is for help fixing my code. I don't expect you to fix directly, but I need to know how to go about figuring out how to fix it. What changed in the API? Is there an upgrade guide/info?

I am going to include more than a little info. I realize that it might be overwhelming. But, I fear that I try to reduce the info too much it will not convey the relevant context.

I'll start with my analysis of my compiler errors that I get. Seems that the struct snd_soc_codec and struct snd_soc_codec_driver were removed. Seems that snd_soc_register_codec() and snd_soc_unregister_codec() were removed. What replaces these things? What do I need to change to accommodate the removal of these?

Hi,

snd_soc_codec was replaced with snd_soc_component, most of the API translate 1to1. Here try this, see if it works https://chatgpt.com/share/6828e403-d564-8008-b2a4-42c76475a3a4

FYI, here are my compiler errors:

<build-errors> $ make -C ../../.. M=$PWD make: Entering directory '/home/steve/code/compton-kernel' CC [M] /home/steve/code/compton-kernel/drivers/compton/dep-imx8-i2s/dep_i2s.o /home/steve/code/compton-kernel/drivers/compton/dep-imx8-i2s/dep_i2s.c:110:38: warning: 'struct snd_soc_codec' declared inside parameter list will not be visible outside of this definition or declaration 110 | static int codec_driver_probe(struct snd_soc_codec *codec) | ^~~~~~~~~~~~~ In file included from ./include/linux/device.h:15, from ./include/linux/platform_device.h:13, from ./include/linux/of_device.h:5, from /home/steve/code/compton-kernel/drivers/compton/dep-imx8-i2s/dep_i2s.c:7: /home/steve/code/compton-kernel/drivers/compton/dep-imx8-i2s/dep_i2s.c: In function 'codec_driver_probe': /home/steve/code/compton-kernel/drivers/compton/dep-imx8-i2s/dep_i2s.c:112:19: error: invalid use of undefined type 'struct snd_soc_codec' 112 | dev_info(codec->dev, "Entered %s", __func__); | ^~ ./include/linux/dev_printk.h:110:25: note: in definition of macro 'dev_printk_index_wrap' 110 | _p_func(dev, fmt, ##__VA_ARGS__); \ | ^~~ /home/steve/code/compton-kernel/drivers/compton/dep-imx8-i2s/dep_i2s.c:112:5: note: in expansion of macro 'dev_info' 112 | dev_info(codec->dev, "Entered %s", __func__); | ^~~~~~~~ /home/steve/code/compton-kernel/drivers/compton/dep-imx8-i2s/dep_i2s.c: At top level: /home/steve/code/compton-kernel/drivers/compton/dep-imx8-i2s/dep_i2s.c:116:21: error: variable 'codec_driver' has initializer but incomplete type 116 | static const struct snd_soc_codec_driver codec_driver = { | ^~~~~~~~~~~~~~~~~~~~ /home/steve/code/compton-kernel/drivers/compton/dep-imx8-i2s/dep_i2s.c:117:6: error: 'const struct snd_soc_codec_driver' has no member named 'probe' 117 | .probe = codec_driver_probe, | ^~~~~ /home/steve/code/compton-kernel/drivers/compton/dep-imx8-i2s/dep_i2s.c:117:14: warning: excess elements in struct initializer 117 | .probe = codec_driver_probe, | ^~~~~~~~~~~~~~~~~~ /home/steve/code/compton-kernel/drivers/compton/dep-imx8-i2s/dep_i2s.c :117:14: note: (near initialization for 'codec_driver') /home/steve/code/compton-kernel/drivers/compton/dep-imx8-i2s/dep_i2s.c:118:6: error: 'const struct snd_soc_codec_driver' has no member named 'component_driver' 118 | .component_driver = { | ^~~~~~~~~~~~~~~~ /home/steve/code/compton-kernel/drivers/compton/dep-imx8-i2s/dep_i2s.c:118:25: error: extra brace group at end of initializer 118 | .component_driver = { | ^ /home/steve/code/compton-kernel/drivers/compton/dep-imx8-i2s/dep_i2s.c :118:25: note: (near initialization for 'codec_driver') /home/steve/code/compton-kernel/drivers/compton/dep-imx8-i2s/dep_i2s.c :118:25: warning: excess elements in struct initializer /home/steve/code/compton-kernel/drivers/compton/dep-imx8-i2s/dep_i2s.c :118:25: note: (near initialization for 'codec_driver') /home/steve/code/compton-kernel/drivers/compton/dep-imx8-i2s/dep_i2s.c: In function 'platform_driver_probe_': /home/steve/code/compton-kernel/drivers/compton/dep-imx8-i2s/dep_i2s.c:153:12: error: implicit declaration of function 'snd_soc_register_codec'; did you mean 'snd_soc_register_dai'? [-Werror=implicit-function-declaration] 153 | stat = snd_soc_register_codec(&pdev->dev, &codec_driver, &dai_driver, 1); | ^~~~~~~~~~~~~~~~~~~~~~ | snd_soc_register_dai /home/steve/code/compton-kernel/drivers/compton/dep-imx8-i2s/dep_i2s.c: In function 'platform_driver_remove': /home/steve/code/compton-kernel/drivers/compton/dep-imx8-i2s/dep_i2s.c:166:5: error: implicit declaration of function 'snd_soc_unregister_codec'; did you mean 'snd_soc_unregister_dai'? [-Werror=implicit-function-declaration] 166 | snd_soc_unregister_codec(&pdev->dev); | ^~~~~~~~~~~~~~~~~~~~~~~~ | snd_soc_unregister_dai /home/steve/code/compton-kernel/drivers/compton/dep-imx8-i2s/dep_i2s.c: At top level: /home/steve/code/compton-kernel/drivers/compton/dep-imx8-i2s/dep_i2s.c:116:42: error: storage size of 'codec_driver' isn't known 116 | static const struct snd_soc_codec_driver codec_driver = { | ^~~~~~~~~~~~ cc1: some warnings being treated as errors make[2]: *** [scripts/Makefile.build:243: /home/steve/code/compton-kernel/drivers/compton/dep-imx8-i2s/dep_i2s.o ] Error 1 make[1]: *** [/home/steve/code/compton-kernel/Makefile:1921: /home/steve/code/compton-kernel/drivers/compton/dep-imx8-i2s] Error 2 make: *** [Makefile:234: __sub-make] Error 2 make: Leaving directory '/home/steve/code/compton-kernel' </build-errors>

My code (for 4.14 kernel)

Here's my driver code. The macro INCLUDE_PROBLEMATIC_CODE is used around each chuck that fails to compile. If not defined, the code does compile, but of course is missing important parts.

<my-code> #define INCLUDE_PROBLEMATIC_CODE /* * Audindate Dante Embedded Platform (DEP) I2S Codec (ALSA SoC) driver; Linux module * Supports sample rates, bit depths and TDM modes for Dante devices. */ #include <linux/module.h> #include <linux/of_device.h> #include <linux/clk.h> #include <sound/soc.h> #include <sound/pcm.h> #include <linux/printk.h>

#define DEP_I2S_PCM_RATES (SNDRV_PCM_RATE_44100 | SNDRV_PCM_RATE_48000 | \ SNDRV_PCM_RATE_88200 | SNDRV_PCM_RATE_96000 | \ SNDRV_PCM_RATE_176400 | SNDRV_PCM_RATE_192000) #define DEP_I2S_PCM_FORMATS ( SNDRV_PCM_FMTBIT_S16_LE | \ SNDRV_PCM_FMTBIT_S24_LE | \ SNDRV_PCM_FMTBIT_S32_LE )

// for future use struct instance_state { unsigned int dummy_holder; };

static const struct snd_soc_dapm_widget widgets[] = { SND_SOC_DAPM_DAC("DAC", "Playback", SND_SOC_NOPM, 0, 0), SND_SOC_DAPM_ADC("ADC", "Capture", SND_SOC_NOPM, 0, 0), SND_SOC_DAPM_OUTPUT("LINEVOUT"), SND_SOC_DAPM_INPUT("LINEVIN"), };

static const struct snd_soc_dapm_route routes[] = { { "LINEVOUT", NULL, "DAC" }, { "ADC", NULL, "LINEVIN" }, };

static int set_fmt(struct snd_soc_dai *dai, unsigned int fmt) { switch (fmt & SND_SOC_DAIFMT_FORMAT_MASK) { case SND_SOC_DAIFMT_I2S: // supported break; case SND_SOC_DAIFMT_LEFT_J: // supported break; default: // all other formats unsupported dev_err(dai->dev, "Invalid DAI format: DEP I2S only supports left justified and I2S, got 0x%04X", fmt); return -EINVAL; }

 switch (fmt & SND_SOC_DAIFMT_MASTER_MASK) {
     // codec as bit master and frame master (or external clock generator)
     // note that jumpers on DEP-EVK-IMX8 must be set correctly
     case SND_SOC_DAIFMT_CBM_CFM:
         // supported
         break;
     // codec as bit slave and frame slave (ie clocks driven from SOC)
     case SND_SOC_DAIFMT_CBS_CFS:
         // supported
         break;
     default:
         // all others unsupported
         dev_err(dai->dev, "Invalid DAI format: DEP I2S only supports CODEC as bit and frame clock master, got 0x%04X", fmt);
         return -EINVAL;
 }

 switch (fmt & SND_SOC_DAIFMT_INV_MASK) {
     default:
         // support bit and frame inversion
         break;
 }

 dev_info(dai->dev, "Set fmt to %u", fmt);
 return 0;

}

static struct snd_soc_dai_ops dep_i2s_dai_ops = { .set_fmt = set_fmt, // add mute here };

struct snd_soc_dai_driver dai_driver = { .name = "dep-i2s", .playback = { .stream_name = "Playback", .channels_min = 1, .channels_max = 16, .rate_min = 44100, .rate_max = 192000, .rates = DEP_I2S_PCM_RATES, .formats = DEP_I2S_PCM_FORMATS, }, .capture = { .stream_name = "Capture", .channels_min = 1, .channels_max = 16, .rate_min = 44100, .rate_max = 192000, .rates = DEP_I2S_PCM_RATES, .formats = DEP_I2S_PCM_FORMATS, }, .ops = &dep_i2s_dai_ops, .symmetric_rate = 1, };

#ifdef INCLUDE_PROBLEMATIC_CODE

// Dummy probe static int codec_driver_probe(struct snd_soc_codec *codec) { dev_info(codec->dev, "Entered %s", __func__); return 0; }

static const struct snd_soc_codec_driver codec_driver = { .probe = codec_driver_probe, .component_driver = { .dapm_widgets = widgets, .num_dapm_widgets = ARRAY_SIZE(widgets), .dapm_routes = routes, .num_dapm_routes = ARRAY_SIZE(routes), }, };

#endif

#if defined(CONFIG_OF) static const struct of_device_id match_table[] = { {.compatible = "audinate,dep_i2s"}, {} }; MODULE_DEVICE_TABLE(of, match_table); #endif

static int platform_driver_probe_(struct platform_device *pdev) { dev_info(&pdev->dev, "Entered %s", __func__);

 int stat = 0;

 struct instance_state *instance_state = devm_kzalloc(&pdev->dev, sizeof(struct instance_state), GFP_KERNEL);
 if (instance_state == NULL) {
     return -ENOMEM;
 }

 platform_set_drvdata(pdev, instance_state);

 dev_info(&pdev->dev, "Codec probe pt 2");

#ifdef INCLUDE_PROBLEMATIC_CODE // 1 == number of DAIs, might need to be 2 for dual direction, or for 2* sai? stat = snd_soc_register_codec(&pdev->dev, &codec_driver, &dai_driver, 1); if (stat < 0) { dev_err(&pdev->dev, "Failed to register codec: %d", stat); } #endif

 return stat;

}

static int platform_driver_remove(struct platform_device *pdev) { dev_info(&pdev->dev, "Entered %s", __func__); #ifdef INCLUDE_PROBLEMATIC_CODE snd_soc_unregister_codec(&pdev->dev); #endif return 0; }

static struct platform_driver platform_driver = { .probe = platform_driver_probe_, .remove = platform_driver_remove, .driver = { .name = "dep-i2s-codec", .of_match_table = of_match_ptr(match_table), }, };

module_platform_driver(platform_driver);

MODULE_DESCRIPTION("Audinate DEP generic I2S ASoC codec"); MODULE_AUTHOR("James Stuart opensource@audinate.com"); MODULE_ALIAS("platform:dep-i2s-codec"); MODULE_LICENSE("GPL");

</my-code>

Steve Broshar Palmer Wireless Medtech