[PATCH] staging: greybus: audio: split topology get into size and data calls

[adi25charis@gmail.com]

From: Aditya Chari S <adi25charis@gmail.com>

gb_audio_gb_get_topology() combined three separate responsibilities
into a single call: querying the topology size, allocating a buffer
for it, and fetching the topology data into that buffer. This left
callers with no way to perform any of these steps independently, and
forced the kzalloc() allocation to live inside the protocol-layer
driver rather than the caller, as already flagged by a FIXME comment
at the call site in audio_module.c.

Split the function into two:

  gb_audio_gb_get_topology_size() - queries only the topology size
  gb_audio_gb_get_topology()      - fetches topology data into a
                                     caller-supplied buffer of a
                                     given size

Update the only caller, gb_audio_probe() in audio_module.c, to query
the size first, allocate the topology buffer itself, then fetch the
data into it, freeing the buffer via the existing free_topology error
path on failure.

This resolves both the "TODO: Split into separate calls" comment
above the original function in audio_gb.c and the FIXME comment at
the call site in audio_module.c, both of which are removed as part
of this change.

No functional change in behavior for the existing probe path.

Compile-tested with W=1, sparse (C=2), and checkpatch.pl; all clean
on the three changed files (audio_gb.c, audio_module.c, audio_codec.h).

Signed-off-by: Aditya Chari S <adi25charis@gmail.com>
---
 drivers/staging/greybus/audio_codec.h  |  4 +++-
 drivers/staging/greybus/audio_gb.c     | 33 ++++++++++----------------
 drivers/staging/greybus/audio_module.c | 21 +++++++++++-----
 3 files changed, 31 insertions(+), 27 deletions(-)

diff --git a/drivers/staging/greybus/audio_codec.h b/drivers/staging/greybus/audio_codec.h
index f3f7a7ec6..be5a2a86b 100644
--- a/drivers/staging/greybus/audio_codec.h
+++ b/drivers/staging/greybus/audio_codec.h
@@ -178,8 +178,10 @@ int gbaudio_register_module(struct gbaudio_module_info *module);
 void gbaudio_unregister_module(struct gbaudio_module_info *module);
 
 /* protocol related */
+int gb_audio_gb_get_topology_size(struct gb_connection *connection,
+				  u16 *size);
 int gb_audio_gb_get_topology(struct gb_connection *connection,
-			     struct gb_audio_topology **topology);
+			     struct gb_audio_topology *topology, u16 size);
 int gb_audio_gb_get_control(struct gb_connection *connection,
 			    u8 control_id, u8 index,
 			    struct gb_audio_ctl_elem_value *value);
diff --git a/drivers/staging/greybus/audio_gb.c b/drivers/staging/greybus/audio_gb.c
index 9d8994fdb..e6356643d 100644
--- a/drivers/staging/greybus/audio_gb.c
+++ b/drivers/staging/greybus/audio_gb.c
@@ -8,13 +8,10 @@
 #include <linux/greybus.h>
 #include "audio_codec.h"
 
-/* TODO: Split into separate calls */
-int gb_audio_gb_get_topology(struct gb_connection *connection,
-			     struct gb_audio_topology **topology)
+int gb_audio_gb_get_topology_size(struct gb_connection *connection,
+				  u16 *size)
 {
 	struct gb_audio_get_topology_size_response size_resp;
-	struct gb_audio_topology *topo;
-	u16 size;
 	int ret;
 
 	ret = gb_operation_sync(connection, GB_AUDIO_TYPE_GET_TOPOLOGY_SIZE,
@@ -22,24 +19,20 @@ int gb_audio_gb_get_topology(struct gb_connection *connection,
 	if (ret)
 		return ret;
 
-	size = le16_to_cpu(size_resp.size);
-	if (size < sizeof(*topo))
-		return -ENODATA;
-
-	topo = kzalloc(size, GFP_KERNEL);
-	if (!topo)
-		return -ENOMEM;
+	*size = le16_to_cpu(size_resp.size);
 
-	ret = gb_operation_sync(connection, GB_AUDIO_TYPE_GET_TOPOLOGY, NULL, 0,
-				topo, size);
-	if (ret) {
-		kfree(topo);
-		return ret;
-	}
+	return 0;
+}
+EXPORT_SYMBOL_GPL(gb_audio_gb_get_topology_size);
 
-	*topology = topo;
+int gb_audio_gb_get_topology(struct gb_connection *connection,
+			     struct gb_audio_topology *topology, u16 size)
+{
+	if (size < sizeof(*topology))
+		return -ENODATA;
 
-	return 0;
+	return gb_operation_sync(connection, GB_AUDIO_TYPE_GET_TOPOLOGY, NULL, 0,
+				 topology, size);
 }
 EXPORT_SYMBOL_GPL(gb_audio_gb_get_topology);
 
diff --git a/drivers/staging/greybus/audio_module.c b/drivers/staging/greybus/audio_module.c
index 12c376c47..1163cf093 100644
--- a/drivers/staging/greybus/audio_module.c
+++ b/drivers/staging/greybus/audio_module.c
@@ -239,6 +239,7 @@ static int gb_audio_probe(struct gb_bundle *bundle,
 	struct gb_audio_manager_module_descriptor desc;
 	struct gbaudio_data_connection *dai, *_dai;
 	int ret, i;
+	u16 size;
 	struct gb_audio_topology *topology;
 
 	/* There should be at least one Management and one Data cport */
@@ -304,16 +305,24 @@ static int gb_audio_probe(struct gb_bundle *bundle,
 	}
 	gbmodule->dev_id = gbmodule->mgmt_connection->intf->interface_id;
 
-	/*
-	 * FIXME: malloc for topology happens via audio_gb driver
-	 * should be done within codec driver itself
-	 */
-	ret = gb_audio_gb_get_topology(gbmodule->mgmt_connection, &topology);
+	ret = gb_audio_gb_get_topology_size(gbmodule->mgmt_connection, &size);
 	if (ret) {
-		dev_err(dev, "%d:Error while fetching topology\n", ret);
+		dev_err(dev, "%d:Error while fetching topology size\n", ret);
+		goto disable_connection;
+	}
+
+	topology = kzalloc(size, GFP_KERNEL);
+	if (!topology) {
+		ret = -ENOMEM;
 		goto disable_connection;
 	}
 
+	ret = gb_audio_gb_get_topology(gbmodule->mgmt_connection, topology, size);
+	if (ret) {
+		dev_err(dev, "%d:Error while fetching topology\n", ret);
+		goto free_topology;
+	}
+
 	/* process topology data */
 	ret = gbaudio_tplg_parse_data(gbmodule, topology);
 	if (ret) {
-- 
2.53.0