[PATCH AUTOSEL 6.18-6.12] ASoC: rockchip: Fix Wvoid-pointer-to-enum-cast warning (again)

[Sasha Levin]

From: Krzysztof Kozlowski <krzysztof.kozlowski at oss.qualcomm.com>

[ Upstream commit 57d508b5f718730f74b11e0dc9609ac7976802d1 ]

'version' is an enum, thus cast of pointer on 64-bit compile test with
clang W=1 causes:

  rockchip_pdm.c:583:17: error: cast to smaller integer type 'enum rk_pdm_version' from 'const void *' [-Werror,-Wvoid-pointer-to-enum-cast]

This was already fixed in commit 49a4a8d12612 ("ASoC: rockchip: Fix
Wvoid-pointer-to-enum-cast warning") but then got bad in
commit 9958d85968ed ("ASoC: Use device_get_match_data()").

Discussion on LKML also pointed out that 'uintptr_t' is not the correct
type and either 'kernel_ulong_t' or 'unsigned long' should be used,
with several arguments towards the latter [1].

Link: https://lore.kernel.org/r/CAMuHMdX7t=mabqFE5O-Cii3REMuyaePHmqX+j_mqyrn6XXzsoA@mail.gmail.com/ [1]
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski at oss.qualcomm.com>
Link: https://patch.msgid.link/20251203141644.106459-2-krzysztof.kozlowski@oss.qualcomm.com
Signed-off-by: Mark Brown <broonie at kernel.org>
Signed-off-by: Sasha Levin <sashal at kernel.org>
---

LLM Generated explanations, may be completely bogus:

## Summary Analysis

### What the commit fixes
This is a **build fix** that prevents a compilation error when building
with clang and W=1:
```
error: cast to smaller integer type 'enum rk_pdm_version' from 'const
void *' [-Werror,-Wvoid-pointer-to-enum-cast]
```

The issue is that on 64-bit systems, casting directly from `const void
*` (64 bits) to an enum (typically 32 bits) triggers a truncation
warning. Using `(unsigned long)` as an intermediate cast avoids this
because `unsigned long` matches the pointer size.

### Classification
This falls clearly into the **BUILD FIX** exception category which is
explicitly allowed for stable trees. Build fixes that prevent
compilation are critical for users who need to build the kernel.

### Scope and Risk
- **Change**: Single line - only changing the cast type
- **Files touched**: 1 file
- **Risk**: Extremely low - the runtime behavior is identical; only the
  compile-time representation differs
- **Functional equivalence**: The value stored in `pdm->version` is the
  same either way

### Applicability to Stable Trees
The regressing commit 9958d85968ed went into v6.7-rc1. Therefore:
- Stable trees **v6.6.y and earlier**: NOT affected (don't have the
  regression)
- Stable trees **v6.7.y and later**: Affected and would benefit from
  this fix

### Stable Criteria Assessment
| Criterion | Assessment |
|-----------|------------|
| Obviously correct | ✓ Yes - standard pattern for void pointer to enum
cast |
| Fixes real bug | ✓ Yes - compilation failure |
| Small scope | ✓ Yes - 1 line change |
| No new features | ✓ Correct - pure bug fix |
| Tested | ✓ Accepted by maintainer |

### Additional Factors
- This is a **regression fix** - the same issue was previously fixed in
  commit 49a4a8d12612 but regressed
- LKML discussion confirms `unsigned long` as the appropriate fix
- Signed off by both author and subsystem maintainer (Mark Brown)

### Risk vs Benefit
- **Risk**: Near zero - compile-time only change, no runtime behavior
  modification
- **Benefit**: Enables compilation with clang W=1 on 64-bit platforms

This is an excellent stable backport candidate. It's a minimal, low-risk
build fix that allows users to compile the kernel in a common
configuration. Build fixes are explicitly mentioned as appropriate for
stable trees, and this one is as safe as they come - a single-line cast
change with no runtime impact.

**YES**

 sound/soc/rockchip/rockchip_pdm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/soc/rockchip/rockchip_pdm.c b/sound/soc/rockchip/rockchip_pdm.c
index c1ee470ec6079..c69cdd6f24994 100644
--- a/sound/soc/rockchip/rockchip_pdm.c
+++ b/sound/soc/rockchip/rockchip_pdm.c
@@ -580,7 +580,7 @@ static int rockchip_pdm_probe(struct platform_device *pdev)
 	if (!pdm)
 		return -ENOMEM;
 
-	pdm->version = (enum rk_pdm_version)device_get_match_data(&pdev->dev);
+	pdm->version = (unsigned long)device_get_match_data(&pdev->dev);
 	if (pdm->version == RK_PDM_RK3308) {
 		pdm->reset = devm_reset_control_get(&pdev->dev, "pdm-m");
 		if (IS_ERR(pdm->reset))
-- 
2.51.0