In i2sbus_resume(), skip devices with an empty codec list, which avoids
using an uninitialized 'sysclock_factor' in the 32-bit format path in
i2sbus_pcm_prepare().

In i2sbus_pcm_prepare(), replace two list_for_each_entry() loops with a
single list_first_entry() now that the codec list is guaranteed to be
non-empty by all callers.

Fixes: f3d9478b2ce4 ("[ALSA] snd-aoa: add snd-aoa")
Cc: stable@vger.kernel.org
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
Changes in v2:
- Skip devices with no codecs in i2sbus_resume() and use
  list_first_entry() in i2sbus_pcm_prepare() now that the codec list is
  guaranteed to be non-empty by all callers (Takashi)
- Link to v1: https://lore.kernel.org/lkml/20260309114159.765304-3-thorsten.blum@linux.dev/
---
 sound/aoa/soundbus/i2sbus/core.c |  3 +++
 sound/aoa/soundbus/i2sbus/pcm.c  | 16 +++++-----------
 2 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/sound/aoa/soundbus/i2sbus/core.c b/sound/aoa/soundbus/i2sbus/core.c
index f974b96e98cd..22c956267f4e 100644
--- a/sound/aoa/soundbus/i2sbus/core.c
+++ b/sound/aoa/soundbus/i2sbus/core.c
@@ -405,6 +405,9 @@ static int i2sbus_resume(struct macio_dev* dev)
 	int err, ret = 0;
 
 	list_for_each_entry(i2sdev, &control->list, item) {
+		if (list_empty(&i2sdev->sound.codec_list))
+			continue;
+
 		/* reset i2s bus format etc. */
 		i2sbus_pcm_prepare_both(i2sdev);
 
diff --git a/sound/aoa/soundbus/i2sbus/pcm.c b/sound/aoa/soundbus/i2sbus/pcm.c
index aff99003d833..97c807e67d56 100644
--- a/sound/aoa/soundbus/i2sbus/pcm.c
+++ b/sound/aoa/soundbus/i2sbus/pcm.c
@@ -383,6 +383,9 @@ static int i2sbus_pcm_prepare(struct i2sbus_dev *i2sdev, int in)
 	/* set stop command */
 	command->command = cpu_to_le16(DBDMA_STOP);
 
+	cii = list_first_entry(&i2sdev->sound.codec_list,
+			       struct codec_info_item, list);
+
 	/* ok, let's set the serial format and stuff */
 	switch (runtime->format) {
 	/* 16 bit formats */
@@ -390,13 +393,7 @@ static int i2sbus_pcm_prepare(struct i2sbus_dev *i2sdev, int in)
 	case SNDRV_PCM_FORMAT_U16_BE:
 		/* FIXME: if we add different bus factors we need to
 		 * do more here!! */
-		bi.bus_factor = 0;
-		list_for_each_entry(cii, &i2sdev->sound.codec_list, list) {
-			bi.bus_factor = cii->codec->bus_factor;
-			break;
-		}
-		if (!bi.bus_factor)
-			return -ENODEV;
+		bi.bus_factor = cii->codec->bus_factor;
 		input_16bit = 1;
 		break;
 	case SNDRV_PCM_FORMAT_S32_BE:
@@ -410,10 +407,7 @@ static int i2sbus_pcm_prepare(struct i2sbus_dev *i2sdev, int in)
 		return -EINVAL;
 	}
 	/* we assume all sysclocks are the same! */
-	list_for_each_entry(cii, &i2sdev->sound.codec_list, list) {
-		bi.sysclock_factor = cii->codec->sysclock_factor;
-		break;
-	}
+	bi.sysclock_factor = cii->codec->sysclock_factor;
 
 	if (clock_and_divisors(bi.sysclock_factor,
 			       bi.bus_factor,

On Tue, 10 Mar 2026 11:29:20 +0100,
Thorsten Blum wrote:
> --- a/sound/aoa/soundbus/i2sbus/core.c
> +++ b/sound/aoa/soundbus/i2sbus/core.c
> @@ -405,6 +405,9 @@ static int i2sbus_resume(struct macio_dev* dev)
>  	int err, ret = 0;
>  
>  	list_for_each_entry(i2sdev, &control->list, item) {
> +		if (list_empty(&i2sdev->sound.codec_list))
> +			continue;

This can be even outside the loop and immediately return 0, as the
remaining part is also the loop of codec_list.

  	int err, ret = 0;
  
 +	if (list_empty(&i2sdev->sound.codec_list))
 +		return 0;
 +
  	list_for_each_entry(i2sdev, &control->list, item) {
  		/* reset i2s bus format etc. */
  		i2sbus_pcm_prepare_both(i2sdev);


thanks,

Takashi

On 10. Mar 2026, at 16:07, Takashi Iwai wrote:
> On Tue, 10 Mar 2026 11:29:20 +0100, Thorsten Blum wrote:
>> --- a/sound/aoa/soundbus/i2sbus/core.c
>> +++ b/sound/aoa/soundbus/i2sbus/core.c
>> @@ -405,6 +405,9 @@ static int i2sbus_resume(struct macio_dev* dev)
>> 	int err, ret = 0;
>> 
>> 	list_for_each_entry(i2sdev, &control->list, item) {
>> +		if (list_empty(&i2sdev->sound.codec_list))
>> +			continue;
> 
> This can be even outside the loop and immediately return 0, as the
> remaining part is also the loop of codec_list.

The i2sdev pointer is only assigned by the outer list_for_each_entry(),
which iterates the controller's device list. Since each device has its
own codec list, list_empty(&i2sdev->sound.codec_list) must be checked
inside the loop; before the loop i2sdev is uninitialized.

Thanks,
Thorsten

On Tue, 10 Mar 2026 17:30:01 +0100,
Thorsten Blum wrote:
> 
> On 10. Mar 2026, at 16:07, Takashi Iwai wrote:
> > On Tue, 10 Mar 2026 11:29:20 +0100, Thorsten Blum wrote:
> >> --- a/sound/aoa/soundbus/i2sbus/core.c
> >> +++ b/sound/aoa/soundbus/i2sbus/core.c
> >> @@ -405,6 +405,9 @@ static int i2sbus_resume(struct macio_dev* dev)
> >> 	int err, ret = 0;
> >> 
> >> 	list_for_each_entry(i2sdev, &control->list, item) {
> >> +		if (list_empty(&i2sdev->sound.codec_list))
> >> +			continue;
> > 
> > This can be even outside the loop and immediately return 0, as the
> > remaining part is also the loop of codec_list.
> 
> The i2sdev pointer is only assigned by the outer list_for_each_entry(),
> which iterates the controller's device list. Since each device has its
> own codec list, list_empty(&i2sdev->sound.codec_list) must be checked
> inside the loop; before the loop i2sdev is uninitialized.

Ah indeed.  Now I applied to for-next branch.


thanks,

Takashi