[libcamera-devel] [PATCH] ipa: Allow short-circuiting the ipa_operations

[Laurent Pinchart]

When an IPA module is loaded without isolation and implements the
IPAInterface internally, going through ipa_operations is a waste of
time. Add an operation to retrieve the IPAInterface, and use it directly
in the IPAContextWrapper.

Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
---
 include/ipa/ipa_interface.h                 |  1 +
 src/ipa/libipa/ipa_interface_wrapper.cpp    |  8 ++++++++
 src/ipa/libipa/ipa_interface_wrapper.h      |  1 +
 src/libcamera/include/ipa_context_wrapper.h |  1 +
 src/libcamera/ipa_context_wrapper.cpp       |  8 +++++++-
 src/libcamera/ipa_interface.cpp             | 15 +++++++++++++++
 6 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/include/ipa/ipa_interface.h b/include/ipa/ipa_interface.h
index a0dfce96fd1c..7c7771b97e30 100644
--- a/include/ipa/ipa_interface.h
+++ b/include/ipa/ipa_interface.h
@@ -18,6 +18,7 @@ struct ipa_context {
 struct ipa_operations {
 	void (*destroy)(struct ipa_context *ctx);
 	void (*init)(struct ipa_context *ctx);
+	void *(*get_interface)(struct ipa_context *ctx);
 };
 
 #ifdef __cplusplus
diff --git a/src/ipa/libipa/ipa_interface_wrapper.cpp b/src/ipa/libipa/ipa_interface_wrapper.cpp
index 0a58b5e8f7e1..a39b699ad600 100644
--- a/src/ipa/libipa/ipa_interface_wrapper.cpp
+++ b/src/ipa/libipa/ipa_interface_wrapper.cpp
@@ -68,6 +68,13 @@ void IPAInterfaceWrapper::init(struct ipa_context *_ctx)
 	ctx->ipa->init();
 }
 
+void *IPAInterfaceWrapper::get_interface(struct ipa_context *_ctx)
+{
+	IPAInterfaceWrapper *ctx = static_cast<IPAInterfaceWrapper *>(_ctx);
+
+	return ctx->ipa;
+}
+
 #ifndef __DOXYGEN__
 /*
  * This construct confuses Doygen and makes it believe that all members of the
@@ -76,6 +83,7 @@ void IPAInterfaceWrapper::init(struct ipa_context *_ctx)
 const struct ipa_operations IPAInterfaceWrapper::operations = {
 	.destroy = &IPAInterfaceWrapper::destroy,
 	.init = &IPAInterfaceWrapper::init,
+	.get_interface = &IPAInterfaceWrapper::get_interface,
 };
 #endif
 
diff --git a/src/ipa/libipa/ipa_interface_wrapper.h b/src/ipa/libipa/ipa_interface_wrapper.h
index 582d787d27ed..66aa387ac191 100644
--- a/src/ipa/libipa/ipa_interface_wrapper.h
+++ b/src/ipa/libipa/ipa_interface_wrapper.h
@@ -19,6 +19,7 @@ public:
 private:
 	static void destroy(struct ipa_context *ctx);
 	static void init(struct ipa_context *ctx);
+	static void *get_interface(struct ipa_context *ctx);
 
 	static const struct ipa_operations operations;
 
diff --git a/src/libcamera/include/ipa_context_wrapper.h b/src/libcamera/include/ipa_context_wrapper.h
index 879911e8a566..928781429845 100644
--- a/src/libcamera/include/ipa_context_wrapper.h
+++ b/src/libcamera/include/ipa_context_wrapper.h
@@ -21,6 +21,7 @@ public:
 
 private:
 	struct ipa_context *ctx_;
+	IPAInterface *intf_;
 };
 
 } /* namespace libcamera */
diff --git a/src/libcamera/ipa_context_wrapper.cpp b/src/libcamera/ipa_context_wrapper.cpp
index bdd3857731ef..edbfea612515 100644
--- a/src/libcamera/ipa_context_wrapper.cpp
+++ b/src/libcamera/ipa_context_wrapper.cpp
@@ -41,6 +41,10 @@ namespace libcamera {
 IPAContextWrapper::IPAContextWrapper(struct ipa_context *context)
 	: ctx_(context)
 {
+	if (ctx_ && ctx_->ops->get_interface)
+		intf_ = reinterpret_cast<IPAInterface *>(ctx_->ops->get_interface(ctx_));
+	else
+		intf_ = nullptr;
 }
 
 IPAContextWrapper::~IPAContextWrapper()
@@ -51,7 +55,9 @@ IPAContextWrapper::~IPAContextWrapper()
 
 int IPAContextWrapper::init()
 {
-	if (ctx_)
+	if (intf_)
+		intf_->init();
+	else if (ctx_)
 		ctx_->ops->init(ctx_);
 
 	return 0;
diff --git a/src/libcamera/ipa_interface.cpp b/src/libcamera/ipa_interface.cpp
index e95ccecda019..38d284cea114 100644
--- a/src/libcamera/ipa_interface.cpp
+++ b/src/libcamera/ipa_interface.cpp
@@ -40,6 +40,12 @@
  * handlers to communicate with IPA modules. IPA modules may use the
  * IPAInterface API internally if they want to benefit from the data and helper
  * classes offered by libcamera.
+ *
+ * When an IPA module is loaded directly into the libcamera process and uses
+ * the IPAInterface API internally, short-circuiting the path to the
+ * ipa_operations and back to IPAInterface is desirable. To support this, IPA
+ * modules may implement the ipa_operations::get_interface function to return a
+ * pointer to their internal IPAInterface.
  */
 
 /**
@@ -80,6 +86,15 @@
  *
  * \var ipa_operations::init
  * \brief Initialise the ipa_context
+ *
+ * \var ipa_operations::get_interface
+ * \brief Retrieve the IPAInterface implemented by the ipa_context (optional)
+ *
+ * IPA modules may implement this operation to expose their internal
+ * IPAInterface, if any. When implemented, libcamera may at its sole discretion
+ * call it and then bypass the ipa_operations API by calling the IPAInterface
+ * methods directly. IPA modules shall still implement and support the full
+ * ipa_operations API.
  */
 
 namespace libcamera {
-- 
Regards,

Laurent Pinchart