[PATCH v2] ASoC: qcom: lpass-cpu: use DAI table index for playback constraints

[Zimeng Li <me@lizi.moe>]

The DAI ID is a hardware port ID and is not necessarily the index of
the corresponding entry in variant->dai_driver.

When configuring a DAI with LPAIF_I2SCTL_MODE_QUAD01, the probe code
currently uses dai_id to index variant->dai_driver. This is incorrect
for platforms where DAI IDs are sparse. For example, the IPQ806x MI2S
DAI has ID 4 while it is the only entry in the DAI driver table. If
that DAI is configured for QUAD01 and probe reaches this branch, the
code writes beyond that single entry via dai_driver[4] instead of
updating the DAI being processed.

Use the loop index i when updating the current DAI's playback channel
constraints, while retaining dai_id for indexing the hardware-port
specific playback SD-line mode array.

This fixes the incorrect DAI table access for platforms where the DAI
ID does not match its position in the driver table.

Fixes: c223f41c1a52 ("ASoC: qcom: Add four speaker support on MI2S secondary")
Cc: stable@vger.kernel.org
Signed-off-by: Zimeng Li <me@lizi.moe>
Assisted-by: GPT-6 Astra
---
Changes in v2:
- Add stable to Cc.
- Identify the model in the Assisted-by trailer.
- Clarify that the IPQ806x out-of-bounds access requires QUAD01 mode
  and probe to reach the affected branch.

Compile-tested with LLVM for ARM using multi_v7_defconfig with
CONFIG_SND_SOC_STORM=m. The lpass-cpu.o, lpass-ipq806x.o and
lpass-platform.o targets built successfully. Not hardware-tested;
the IPQ806x example is based on static analysis, not a reproduced crash.
The code change is unchanged from v1.

 sound/soc/qcom/lpass-cpu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sound/soc/qcom/lpass-cpu.c b/sound/soc/qcom/lpass-cpu.c
index 242bc16da..079177a6d 100644
--- a/sound/soc/qcom/lpass-cpu.c
+++ b/sound/soc/qcom/lpass-cpu.c
@@ -1234,8 +1234,8 @@ int asoc_qcom_lpass_cpu_platform_probe(struct platform_device *pdev)
 		}
 		if (drvdata->mi2s_playback_sd_mode[dai_id] ==
 			LPAIF_I2SCTL_MODE_QUAD01) {
-			variant->dai_driver[dai_id].playback.channels_min = 4;
-			variant->dai_driver[dai_id].playback.channels_max = 4;
+			variant->dai_driver[i].playback.channels_min = 4;
+			variant->dai_driver[i].playback.channels_max = 4;
 		}
 	}
 

base-commit: 0ed6f7f62318a581fe9698f8a4e98c7ca01160e4
-- 
2.55.0