[PATCH v2] transport: Fix set volume failure with invalid device volume

[PATCH v2] transport: Fix set volume failure with invalid device volume

[Jinwang Li]

When AVRCP is connected earlier than AVDTP, this invalid device volume
causes the A2DP sink to reject the peer's registration for the
EVENT_VOLUME_CHANGED notification. As a result, subsequent attempts to
set the volume fail.

Fix this by ensuring a valid device volume is returned when the device
volume is invalid, allowing volume registration to succeed.

Fixes: fa7828bddd21 ("transport: Fix not being able to initialize volume properly")
Signed-off-by: Jinwang Li <jinwang.li@oss.qualcomm.com>
---
 profiles/audio/transport.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

Changes from v1:
 - Return the max volume from media_transport_get_a2dp_volume()
   when there is no A2DP transport and the device volume is invalid.
 - Restore the default device volume in device_new().
 - Update the commit subject name.
 - Link to v1
   https://lore.kernel.org/all/20260122063640.310090-1-jinwang.li@oss.qualcomm.com/

diff --git a/profiles/audio/transport.c b/profiles/audio/transport.c
index d9feef768..41d8d0a75 100644
--- a/profiles/audio/transport.c
+++ b/profiles/audio/transport.c
@@ -2767,6 +2767,7 @@ static void media_transport_emit_volume(struct media_transport *transport)
 int media_transport_get_a2dp_volume(struct btd_device *dev)
 {
 	GSList *l;
+	int volume;
 
 	if (dev == NULL)
 		return -1;
@@ -2793,7 +2794,11 @@ int media_transport_get_a2dp_volume(struct btd_device *dev)
 	 * of ordering between AVRCP and A2DP session start. (Note BAP+VCP do
 	 * not have this issue.)
 	 */
-	return btd_device_get_volume(dev);
+	volume = btd_device_get_volume(dev);
+	if (volume < 0)
+		volume = 127;
+
+	return volume;
 }
 
 void media_transport_set_a2dp_volume(struct btd_device *dev, int volume)
-- 
2.34.1

RE: [v2] transport: Fix set volume failure with invalid device volume

[bluez.test.bot]

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Dear submitter,

Thank you for submitting the patches to the linux bluetooth mailing list.
This is a CI test results with your patch series:
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---Test result---

Test Summary:
CheckPatch                    PENDING   0.32 seconds
GitLint                       PENDING   0.44 seconds
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BluezMake                     PASS      671.54 seconds
MakeCheck                     PASS      18.65 seconds
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CheckSmatch                   PASS      367.23 seconds
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ScanBuild                     PASS      1069.71 seconds

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Output:

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---
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Re: [PATCH v2] transport: Fix set volume failure with invalid device volume

[Luiz Augusto von Dentz]

Hi Jinwang,

On Thu, Mar 5, 2026 at 3:38 AM Jinwang Li <jinwang.li@oss.qualcomm.com> wrote:
>
> When AVRCP is connected earlier than AVDTP, this invalid device volume
> causes the A2DP sink to reject the peer's registration for the
> EVENT_VOLUME_CHANGED notification. As a result, subsequent attempts to
> set the volume fail.
>
> Fix this by ensuring a valid device volume is returned when the device
> volume is invalid, allowing volume registration to succeed.
>
> Fixes: fa7828bddd21 ("transport: Fix not being able to initialize volume properly")
> Signed-off-by: Jinwang Li <jinwang.li@oss.qualcomm.com>
> ---
>  profiles/audio/transport.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> Changes from v1:
>  - Return the max volume from media_transport_get_a2dp_volume()
>    when there is no A2DP transport and the device volume is invalid.
>  - Restore the default device volume in device_new().
>  - Update the commit subject name.
>  - Link to v1
>    https://lore.kernel.org/all/20260122063640.310090-1-jinwang.li@oss.qualcomm.com/
>
> diff --git a/profiles/audio/transport.c b/profiles/audio/transport.c
> index d9feef768..41d8d0a75 100644
> --- a/profiles/audio/transport.c
> +++ b/profiles/audio/transport.c
> @@ -2767,6 +2767,7 @@ static void media_transport_emit_volume(struct media_transport *transport)
>  int media_transport_get_a2dp_volume(struct btd_device *dev)
>  {
>         GSList *l;
> +       int volume;
>
>         if (dev == NULL)
>                 return -1;
> @@ -2793,7 +2794,11 @@ int media_transport_get_a2dp_volume(struct btd_device *dev)
>          * of ordering between AVRCP and A2DP session start. (Note BAP+VCP do
>          * not have this issue.)
>          */
> -       return btd_device_get_volume(dev);
> +       volume = btd_device_get_volume(dev);
> +       if (volume < 0)
> +               volume = 127;

This doesn't work because the behavior differs depending on the role,
as a source we need to return -1, so I suggest doing this instead:

diff --git a/profiles/audio/avrcp.c b/profiles/audio/avrcp.c
index 724b46c592ff..326dfdab7e3d 100644
--- a/profiles/audio/avrcp.c
+++ b/profiles/audio/avrcp.c
@@ -4296,9 +4296,16 @@ static void target_init(struct avrcp *session)
        if (target->version < 0x0104)
                return;

-       if (avrcp_volume_supported(target))
+       if (avrcp_volume_supported(target)) {
                session->supported_events |=
                                (1 << AVRCP_EVENT_VOLUME_CHANGED);
+               /* Check if transport volume hasn't been initialized then set it
+                * to max so it works properly if the controller attempts to
+                * subscribe to AVRCP_EVENT_VOLUME_CHANGED.
+                */
+               if (media_transport_get_a2dp_volume(session->dev) < 0)
+                       media_transport_set_a2dp_volume(session->dev, 127);
+       }

        session->supported_events |=
                                (1 << AVRCP_EVENT_ADDRESSED_PLAYER_CHANGED) |

> +       return volume;
>  }
>
>  void media_transport_set_a2dp_volume(struct btd_device *dev, int volume)
> --
> 2.34.1
>


-- 
Luiz Augusto von Dentz

Re: [PATCH v2] transport: Fix set volume failure with invalid device volume

[Jinwang Li]

Hi Luiz,

On 3/6/2026 11:00 PM, Luiz Augusto von Dentz wrote:
> Hi Jinwang,
> 
> On Thu, Mar 5, 2026 at 3:38 AM Jinwang Li <jinwang.li@oss.qualcomm.com> wrote:
>>
>> When AVRCP is connected earlier than AVDTP, this invalid device volume
>> causes the A2DP sink to reject the peer's registration for the
>> EVENT_VOLUME_CHANGED notification. As a result, subsequent attempts to
>> set the volume fail.
>>
>> Fix this by ensuring a valid device volume is returned when the device
>> volume is invalid, allowing volume registration to succeed.
>>
>> Fixes: fa7828bddd21 ("transport: Fix not being able to initialize volume properly")
>> Signed-off-by: Jinwang Li <jinwang.li@oss.qualcomm.com>
>> ---
>>   profiles/audio/transport.c | 7 ++++++-
>>   1 file changed, 6 insertions(+), 1 deletion(-)
>>
>> Changes from v1:
>>   - Return the max volume from media_transport_get_a2dp_volume()
>>     when there is no A2DP transport and the device volume is invalid.
>>   - Restore the default device volume in device_new().
>>   - Update the commit subject name.
>>   - Link to v1
>>     https://lore.kernel.org/all/20260122063640.310090-1-jinwang.li@oss.qualcomm.com/
>>
>> diff --git a/profiles/audio/transport.c b/profiles/audio/transport.c
>> index d9feef768..41d8d0a75 100644
>> --- a/profiles/audio/transport.c
>> +++ b/profiles/audio/transport.c
>> @@ -2767,6 +2767,7 @@ static void media_transport_emit_volume(struct media_transport *transport)
>>   int media_transport_get_a2dp_volume(struct btd_device *dev)
>>   {
>>          GSList *l;
>> +       int volume;
>>
>>          if (dev == NULL)
>>                  return -1;
>> @@ -2793,7 +2794,11 @@ int media_transport_get_a2dp_volume(struct btd_device *dev)
>>           * of ordering between AVRCP and A2DP session start. (Note BAP+VCP do
>>           * not have this issue.)
>>           */
>> -       return btd_device_get_volume(dev);
>> +       volume = btd_device_get_volume(dev);
>> +       if (volume < 0)
>> +               volume = 127;
> 
> This doesn't work because the behavior differs depending on the role,
> as a source we need to return -1, so I suggest doing this instead:
> 
> diff --git a/profiles/audio/avrcp.c b/profiles/audio/avrcp.c
> index 724b46c592ff..326dfdab7e3d 100644
> --- a/profiles/audio/avrcp.c
> +++ b/profiles/audio/avrcp.c
> @@ -4296,9 +4296,16 @@ static void target_init(struct avrcp *session)
>          if (target->version < 0x0104)
>                  return;
> 
> -       if (avrcp_volume_supported(target))
> +       if (avrcp_volume_supported(target)) {
>                  session->supported_events |=
>                                  (1 << AVRCP_EVENT_VOLUME_CHANGED);
> +               /* Check if transport volume hasn't been initialized then set it
> +                * to max so it works properly if the controller attempts to
> +                * subscribe to AVRCP_EVENT_VOLUME_CHANGED.
> +                */
> +               if (media_transport_get_a2dp_volume(session->dev) < 0)
> +                       media_transport_set_a2dp_volume(session->dev, 127);
> +       }
> 
>          session->supported_events |=
>                                  (1 << AVRCP_EVENT_ADDRESSED_PLAYER_CHANGED) |
> 

I agree this is the correct approach, and I’ve verified that it resolves 
the volume registration issue. I’ll send a follow-up patch and include 
the credit.

>> +       return volume;
>>   }
>>
>>   void media_transport_set_a2dp_volume(struct btd_device *dev, int volume)
>> --
>> 2.34.1
>>
> 
>