[PATCH AUTOSEL 5.15 2/2] ASoC: Intel: fix SND_SOC_SOF dependencies

[Sasha Levin <sashal@kernel.org>]

From: Arnd Bergmann <arnd@arndb.de>

[ Upstream commit e837b59f8b411b5baf5e3de7a5aea10b1c545a63 ]

It is currently possible to configure a kernel with all Intel SoC
configs as loadable modules, but the board config as built-in. This
causes a link failure in the reference to the snd_soc_sof.ko module:

x86_64-linux-ld: sound/soc/intel/boards/sof_rt5682.o: in function `sof_rt5682_hw_params':
sof_rt5682.c:(.text+0x1f9): undefined reference to `sof_dai_get_mclk'
x86_64-linux-ld: sof_rt5682.c:(.text+0x234): undefined reference to `sof_dai_get_bclk'
x86_64-linux-ld: sound/soc/intel/boards/sof_rt5682.o: in function `sof_rt5682_codec_init':
sof_rt5682.c:(.text+0x3e0): undefined reference to `sof_dai_get_mclk'
x86_64-linux-ld: sound/soc/intel/boards/sof_cs42l42.o: in function `sof_cs42l42_hw_params':
sof_cs42l42.c:(.text+0x2a): undefined reference to `sof_dai_get_bclk'
x86_64-linux-ld: sound/soc/intel/boards/sof_nau8825.o: in function `sof_nau8825_hw_params':
sof_nau8825.c:(.text+0x7f): undefined reference to `sof_dai_get_bclk'
x86_64-linux-ld: sound/soc/intel/boards/sof_da7219.o: in function `da7219_codec_init':
sof_da7219.c:(.text+0xbf): undefined reference to `sof_dai_get_mclk'
x86_64-linux-ld: sound/soc/intel/boards/sof_maxim_common.o: in function `max_98373_hw_params':
sof_maxim_common.c:(.text+0x6f9): undefined reference to `sof_dai_get_tdm_slots'
x86_64-linux-ld: sound/soc/intel/boards/sof_realtek_common.o: in function `rt1015_hw_params':
sof_realtek_common.c:(.text+0x54c): undefined reference to `sof_dai_get_bclk'
x86_64-linux-ld: sound/soc/intel/boards/sof_realtek_common.o: in function `rt1308_hw_params':
sof_realtek_common.c:(.text+0x702): undefined reference to `sof_dai_get_mclk'
x86_64-linux-ld: sound/soc/intel/boards/sof_cirrus_common.o: in function `cs35l41_hw_params':
sof_cirrus_common.c:(.text+0x2f): undefined reference to `sof_dai_get_bclk'

Add an optional dependency on SND_SOC_SOF_INTEL_COMMON, to ensure that whenever
the SOF support is in a loadable module, none of the board code can be built-in.

This may be be a little heavy-handed, but I also don't see a reason why one would
want the boards to be built-in but not the SoC, so it shouldn't actually cause
any usability problems.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20250709145626.64125-1-arnd@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

LLM Generated explanations, may be completely bogus:

Based on my analysis of the commit and its context, here is my
assessment:

**YES** - This commit should be backported to stable kernel trees.

## Extensive Explanation:

### 1. **The commit fixes a critical build failure**
The commit addresses link errors that occur when Intel ASoC board
drivers are built-in (=y) while the SOF core module is built as a
loadable module (=m). The error messages show undefined references to
SOF DAI functions:
- `sof_dai_get_mclk`
- `sof_dai_get_bclk`
- `sof_dai_get_tdm_slots`

These functions are exported from the `snd-sof` module (defined in
`sound/soc/sof/sof-audio.c`), but when board drivers are built-in, they
cannot reference symbols from loadable modules.

### 2. **The fix is minimal and contained**
The change is a single-line modification to the Kconfig dependency:
```diff
-if SND_SOC_INTEL_MACH
+if SND_SOC_INTEL_MACH && (SND_SOC_SOF_INTEL_COMMON ||
!SND_SOC_SOF_INTEL_COMMON)
```

This clever dependency ensures that when `SND_SOC_SOF_INTEL_COMMON` is
built as a module (=m), the Intel machine drivers cannot be built-in
(=y). The `|| !SND_SOC_SOF_INTEL_COMMON` part allows the machine drivers
to be enabled when SOF support is completely disabled.

### 3. **Similar to previous backported fixes**
Looking at the historical commits:
- Commit `8d0872f6239f` (Similar Commit #1) fixed a similar link failure
  for `sof-nau8825` and was backported (YES)
- Commit `f4df4e4042b0` (Similar Commit #4) fixed a similar dependency
  issue with SOF IMX and was backported (YES)

Both of these commits addressed build/link failures caused by incorrect
Kconfig dependencies, just like this commit.

### 4. **No risk of regression**
The change only affects build configuration and doesn't modify any
runtime code. It prevents invalid configurations that would fail to
build anyway. As the commit message states: "it shouldn't actually cause
any usability problems" because there's no practical reason to have
board drivers built-in while the SOF core is a module.

### 5. **Meets stable tree criteria**
- Fixes a real bug (build failure)
- Small and contained change
- No new features or architectural changes
- Similar fixes have been backported before
- Low risk of introducing new issues

The commit follows the pattern of other Kconfig dependency fixes in the
Intel ASoC subsystem that have been successfully backported to stable
trees.

 sound/soc/intel/boards/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/soc/intel/boards/Kconfig b/sound/soc/intel/boards/Kconfig
index 61b71d6c44cfa..960a1bd79489b 100644
--- a/sound/soc/intel/boards/Kconfig
+++ b/sound/soc/intel/boards/Kconfig
@@ -11,7 +11,7 @@ menuconfig SND_SOC_INTEL_MACH
 	 kernel: saying N will just cause the configurator to skip all
 	 the questions about Intel ASoC machine drivers.
 
-if SND_SOC_INTEL_MACH
+if SND_SOC_INTEL_MACH && (SND_SOC_SOF_INTEL_COMMON || !SND_SOC_SOF_INTEL_COMMON)
 
 config SND_SOC_INTEL_USER_FRIENDLY_LONG_NAMES
 	bool "Use more user friendly long card names"
-- 
2.39.5