The i2sbus PCM code uses pi->active to constrain the sibling stream to
an already prepared duplex format and rate in i2sbus_pcm_open().

That state is set from i2sbus_pcm_prepare(), but the current code only
clears it on close. As a result, the sibling stream can inherit stale
constraints after the prepared state has been torn down.

Clear pi->active when hw_params() or hw_free() tears down the prepared
state, and set it again only after prepare succeeds.

Replace the stale FIXME in the duplex constraint comment with a description
of the current driver behavior: i2sbus still programs a single shared
transport configuration for both directions, so mixed formats are not
supported in duplex mode.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202604010125.AvkWBYKI-lkp@intel.com/
Fixes: f3d9478b2ce4 ("[ALSA] snd-aoa: add snd-aoa")
Cc: stable@vger.kernel.org
Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
---
Changes in v2:
- Drop the extra clear of pi->active at the beginning of i2sbus_pcm_prepare()
- Keep the state reset in hw_params() and hw_free() only.
- Fix the newly added .hw_params callbacks to use the proper ALSA prototype
  with struct snd_pcm_hw_params *params, addressing the kernel test robot
  build failure.
- Update the changelog to match the reduced scope of the fix.
- Link to v1: https://patch.msgid.link/20260330-aoa-i2sbus-clear-stale-active-v1-1-47a6c0a3ac9e@gmail.com
---
 sound/aoa/soundbus/i2sbus/pcm.c | 55 ++++++++++++++++++++++++++++++++---------
 1 file changed, 44 insertions(+), 11 deletions(-)

diff --git a/sound/aoa/soundbus/i2sbus/pcm.c b/sound/aoa/soundbus/i2sbus/pcm.c
index 97c807e67d56..63004ece94f9 100644
--- a/sound/aoa/soundbus/i2sbus/pcm.c
+++ b/sound/aoa/soundbus/i2sbus/pcm.c
@@ -165,17 +165,16 @@ static int i2sbus_pcm_open(struct i2sbus_dev *i2sdev, int in)
 	 * currently in use (if any). */
 	hw->rate_min = 5512;
 	hw->rate_max = 192000;
-	/* if the other stream is active, then we can only
-	 * support what it is currently using.
-	 * FIXME: I lied. This comment is wrong. We can support
-	 * anything that works with the same serial format, ie.
-	 * when recording 24 bit sound we can well play 16 bit
-	 * sound at the same time iff using the same transfer mode.
+	/* If the other stream is already prepared, keep this stream
+	 * on the same duplex format and rate.
+	 *
+	 * i2sbus_pcm_prepare() still programs one shared transport
+	 * configuration for both directions, so mixed duplex formats
+	 * are not supported here.
 	 */
 	if (other->active) {
-		/* FIXME: is this guaranteed by the alsa api? */
 		hw->formats &= pcm_format_to_bits(i2sdev->format);
-		/* see above, restrict rates to the one we already have */
+		/* Restrict rates to the one already in use. */
 		hw->rate_min = i2sdev->rate;
 		hw->rate_max = i2sdev->rate;
 	}
@@ -283,6 +282,23 @@ void i2sbus_wait_for_stop_both(struct i2sbus_dev *i2sdev)
 }
 #endif
 
+static void i2sbus_pcm_clear_active(struct i2sbus_dev *i2sdev, int in)
+{
+	struct pcm_info *pi;
+
+	guard(mutex)(&i2sdev->lock);
+
+	get_pcm_info(i2sdev, in, &pi, NULL);
+	pi->active = 0;
+}
+
+static inline int i2sbus_hw_params(struct snd_pcm_substream *substream,
+				   struct snd_pcm_hw_params *params, int in)
+{
+	i2sbus_pcm_clear_active(snd_pcm_substream_chip(substream), in);
+	return 0;
+}
+
 static inline int i2sbus_hw_free(struct snd_pcm_substream *substream, int in)
 {
 	struct i2sbus_dev *i2sdev = snd_pcm_substream_chip(substream);
@@ -291,14 +307,27 @@ static inline int i2sbus_hw_free(struct snd_pcm_substream *substream, int in)
 	get_pcm_info(i2sdev, in, &pi, NULL);
 	if (pi->dbdma_ring.stopping)
 		i2sbus_wait_for_stop(i2sdev, pi);
+	i2sbus_pcm_clear_active(i2sdev, in);
 	return 0;
 }
 
+static int i2sbus_playback_hw_params(struct snd_pcm_substream *substream,
+				     struct snd_pcm_hw_params *params)
+{
+	return i2sbus_hw_params(substream, params, 0);
+}
+
 static int i2sbus_playback_hw_free(struct snd_pcm_substream *substream)
 {
 	return i2sbus_hw_free(substream, 0);
 }
 
+static int i2sbus_record_hw_params(struct snd_pcm_substream *substream,
+				   struct snd_pcm_hw_params *params)
+{
+	return i2sbus_hw_params(substream, params, 1);
+}
+
 static int i2sbus_record_hw_free(struct snd_pcm_substream *substream)
 {
 	return i2sbus_hw_free(substream, 1);
@@ -335,7 +364,6 @@ static int i2sbus_pcm_prepare(struct i2sbus_dev *i2sdev, int in)
 		return -EINVAL;
 
 	runtime = pi->substream->runtime;
-	pi->active = 1;
 	if (other->active &&
 	    ((i2sdev->format != runtime->format)
 	     || (i2sdev->rate != runtime->rate)))
@@ -444,9 +472,11 @@ static int i2sbus_pcm_prepare(struct i2sbus_dev *i2sdev, int in)
 
 	/* early exit if already programmed correctly */
 	/* not locking these is fine since we touch them only in this function */
-	if (in_le32(&i2sdev->intfregs->serial_format) == sfr
-	 && in_le32(&i2sdev->intfregs->data_word_sizes) == dws)
+	if (in_le32(&i2sdev->intfregs->serial_format) == sfr &&
+	    in_le32(&i2sdev->intfregs->data_word_sizes) == dws) {
+		pi->active = 1;
 		return 0;
+	}
 
 	/* let's notify the codecs about clocks going away.
 	 * For now we only do mastering on the i2s cell... */
@@ -484,6 +514,7 @@ static int i2sbus_pcm_prepare(struct i2sbus_dev *i2sdev, int in)
 		if (cii->codec->switch_clock)
 			cii->codec->switch_clock(cii, CLOCK_SWITCH_SLAVE);
 
+	pi->active = 1;
 	return 0;
 }
 
@@ -728,6 +759,7 @@ static snd_pcm_uframes_t i2sbus_playback_pointer(struct snd_pcm_substream
 static const struct snd_pcm_ops i2sbus_playback_ops = {
 	.open =		i2sbus_playback_open,
 	.close =	i2sbus_playback_close,
+	.hw_params =	i2sbus_playback_hw_params,
 	.hw_free =	i2sbus_playback_hw_free,
 	.prepare =	i2sbus_playback_prepare,
 	.trigger =	i2sbus_playback_trigger,
@@ -796,6 +828,7 @@ static snd_pcm_uframes_t i2sbus_record_pointer(struct snd_pcm_substream
 static const struct snd_pcm_ops i2sbus_record_ops = {
 	.open =		i2sbus_record_open,
 	.close =	i2sbus_record_close,
+	.hw_params =	i2sbus_record_hw_params,
 	.hw_free =	i2sbus_record_hw_free,
 	.prepare =	i2sbus_record_prepare,
 	.trigger =	i2sbus_record_trigger,

---
base-commit: 5a8ba15bcbf0cd70cc89d1e1a3d4037b2ab5ccdd
change-id: 20260329-aoa-i2sbus-clear-stale-active-4d3b706cc0ef

Best regards,
--  
Cássio Gabriel <cassiogabrielcontato@gmail.com>