On Qualcomm SoC which has multiple Display Port controllers, using
snd_pcm_add_chmap_ctls() to add chmap controls from every ASoC hdmi codec
instance for a give card fails while adding second instance as the control
with same name "Playback Channel Map" already exists from the first instance.

Fix this by adding a new api wrapper to pass ASoC component name prefix to
avoid such duplicate control naming.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
---
We can also make snd_pcm_add_chmap_ctls to take prefix argument and avoid adding
this new api, but that would touch lots of drivers.


 include/sound/pcm.h  |  7 +++++++
 sound/core/pcm_lib.c | 30 ++++++++++++++++++++++++++++--
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index 27040b472a4f..39efd25b53e3 100644
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -1528,6 +1528,13 @@ int snd_pcm_add_chmap_ctls(struct snd_pcm *pcm, int stream,
 			   unsigned long private_value,
 			   struct snd_pcm_chmap **info_ret);
 
+int snd_pcm_add_chmap_ctls_with_prefix(struct snd_pcm *pcm, int stream,
+				       const struct snd_pcm_chmap_elem *chmap,
+				       int max_channels,
+				       unsigned long private_value,
+				       struct snd_pcm_chmap **info_ret,
+				       const char *prefix);
+
 /**
  * pcm_format_to_bits - Strong-typed conversion of pcm_format to bitwise
  * @pcm_format: PCM format
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index 8b6aeb8a78f7..ed75dd007425 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -2483,11 +2483,12 @@ static void pcm_chmap_ctl_private_free(struct snd_kcontrol *kcontrol)
  * Create channel-mapping control elements assigned to the given PCM stream(s).
  * Return: Zero if successful, or a negative error value.
  */
-int snd_pcm_add_chmap_ctls(struct snd_pcm *pcm, int stream,
+int snd_pcm_add_chmap_ctls_with_prefix(struct snd_pcm *pcm, int stream,
 			   const struct snd_pcm_chmap_elem *chmap,
 			   int max_channels,
 			   unsigned long private_value,
-			   struct snd_pcm_chmap **info_ret)
+			   struct snd_pcm_chmap **info_ret,
+			   const char *prefix)
 {
 	struct snd_pcm_chmap *info;
 	struct snd_kcontrol_new knew = {
@@ -2499,6 +2500,7 @@ int snd_pcm_add_chmap_ctls(struct snd_pcm *pcm, int stream,
 		.get = pcm_chmap_ctl_get,
 		.tlv.c = pcm_chmap_ctl_tlv,
 	};
+	char *name = NULL;
 	int err;
 
 	if (WARN_ON(pcm->streams[stream].chmap_kctl))
@@ -2514,10 +2516,21 @@ int snd_pcm_add_chmap_ctls(struct snd_pcm *pcm, int stream,
 		knew.name = "Playback Channel Map";
 	else
 		knew.name = "Capture Channel Map";
+
+	if (prefix) {
+		name = kasprintf(GFP_KERNEL, "%s %s", prefix, knew.name);
+		if (!name) {
+			kfree(info);
+			return -ENOMEM;
+		}
+		knew.name = name;
+	}
+
 	knew.device = pcm->device;
 	knew.count = pcm->streams[stream].substream_count;
 	knew.private_value = private_value;
 	info->kctl = snd_ctl_new1(&knew, info);
+	kfree(name);
 	if (!info->kctl) {
 		kfree(info);
 		return -ENOMEM;
@@ -2530,5 +2543,18 @@ int snd_pcm_add_chmap_ctls(struct snd_pcm *pcm, int stream,
 	if (info_ret)
 		*info_ret = info;
 	return 0;
+
+}
+EXPORT_SYMBOL_GPL(snd_pcm_add_chmap_ctls_with_prefix);
+
+int snd_pcm_add_chmap_ctls(struct snd_pcm *pcm, int stream,
+			   const struct snd_pcm_chmap_elem *chmap,
+			   int max_channels,
+			   unsigned long private_value,
+			   struct snd_pcm_chmap **info_ret)
+{
+	return snd_pcm_add_chmap_ctls_with_prefix(pcm, stream, chmap,
+						  max_channels, private_value,
+						  info_ret, NULL);
 }
 EXPORT_SYMBOL_GPL(snd_pcm_add_chmap_ctls);
-- 
2.21.0

On Fri, 05 May 2023 18:55:12 +0200,
Srinivas Kandagatla wrote:
> 
> On Qualcomm SoC which has multiple Display Port controllers, using
> snd_pcm_add_chmap_ctls() to add chmap controls from every ASoC hdmi codec
> instance for a give card fails while adding second instance as the control
> with same name "Playback Channel Map" already exists from the first instance.
> 
> Fix this by adding a new api wrapper to pass ASoC component name prefix to
> avoid such duplicate control naming.

It implies that you have conflicting PCM objects with the same PCM
device number from the same card.  How can it be?


Takashi

On 06/05/2023 06:57, Takashi Iwai wrote:
> On Fri, 05 May 2023 18:55:12 +0200,
> Srinivas Kandagatla wrote:
>>
>> On Qualcomm SoC which has multiple Display Port controllers, using
>> snd_pcm_add_chmap_ctls() to add chmap controls from every ASoC hdmi codec
>> instance for a give card fails while adding second instance as the control
>> with same name "Playback Channel Map" already exists from the first instance.
>>
>> Fix this by adding a new api wrapper to pass ASoC component name prefix to
>> avoid such duplicate control naming.
> 
> It implies that you have conflicting PCM objects with the same PCM
> device number from the same card.  How can it be?
Thanks for the inputs, this is only issue with my local changes, Sorry 
for the noise, Please ignore this series.

I had some local changes to debug an issue around pcm device numbering 
with backend dailinks from device tree and frontend dailinks from tplg.
Will start a new thread to discuss this issue.

thanks,
srini
> 
> 
> Takashi