3 files changed, 63 insertions, 0 deletions

diff --git a/kms++/inc/kms++/dmabufframebuffer.h b/kms++/inc/kms++/dmabufframebuffer.h
index 494aa97..95460cb 100644
--- a/kms++/inc/kms++/dmabufframebuffer.h
+++ b/kms++/inc/kms++/dmabufframebuffer.h
@@ -27,6 +27,9 @@ public:
 	uint8_t* map(unsigned plane);
 	int prime_fd(unsigned plane);
 
+	void begin_cpu_access(CpuAccess access);
+	void end_cpu_access();
+
 private:
 	struct FramebufferPlane {
 		uint32_t handle;
@@ -41,6 +44,8 @@ private:
 	struct FramebufferPlane m_planes[4];
 
 	PixelFormat m_format;
+
+	uint32_t m_sync_flags = 0;
 };
 
 }
diff --git a/kms++/inc/kms++/framebuffer.h b/kms++/inc/kms++/framebuffer.h
index 3d43d08..6f90541 100644
--- a/kms++/inc/kms++/framebuffer.h
+++ b/kms++/inc/kms++/framebuffer.h
@@ -5,6 +5,13 @@
 
 namespace kms
 {
+enum class CpuAccess
+{
+	Read,
+	Write,
+	ReadWrite,
+};
+
 class IFramebuffer {
 public:
 	virtual ~IFramebuffer() { }
@@ -20,6 +27,9 @@ public:
 	virtual uint32_t offset(unsigned plane) const { throw std::runtime_error("not implemented"); }
 	virtual uint8_t* map(unsigned plane) { throw std::runtime_error("not implemented"); }
 	virtual int prime_fd(unsigned plane) { throw std::runtime_error("not implemented"); }
+
+	virtual void begin_cpu_access(CpuAccess access) { }
+	virtual void end_cpu_access() { }
 };
 
 class Framebuffer : public DrmObject, public IFramebuffer
diff --git a/kms++/src/dmabufframebuffer.cpp b/kms++/src/dmabufframebuffer.cpp
index cdf7a74..00ab94e 100644
--- a/kms++/src/dmabufframebuffer.cpp
+++ b/kms++/src/dmabufframebuffer.cpp
@@ -4,8 +4,10 @@
 
 #include <stdexcept>
 #include <sys/mman.h>
+#include <sys/ioctl.h>
 #include <xf86drm.h>
 #include <xf86drmMode.h>
+#include <linux/dma-buf.h>
 
 #include <kms++/kms++.h>
 
@@ -78,4 +80,50 @@ int DmabufFramebuffer::prime_fd(unsigned plane)
 	return p.prime_fd;
 }
 
+void DmabufFramebuffer::begin_cpu_access(CpuAccess access)
+{
+	if (m_sync_flags != 0)
+		throw runtime_error("begin_cpu sync already started");
+
+	switch (access) {
+	case CpuAccess::Read:
+		m_sync_flags = DMA_BUF_SYNC_READ;
+		break;
+	case CpuAccess::Write:
+		m_sync_flags = DMA_BUF_SYNC_WRITE;
+		break;
+	case CpuAccess::ReadWrite:
+		m_sync_flags = DMA_BUF_SYNC_RW;
+		break;
+	}
+
+	dma_buf_sync dbs {
+		.flags = DMA_BUF_SYNC_START | m_sync_flags
+	};
+
+	for (uint32_t p = 0; p < m_num_planes; ++p) {
+		int r = ioctl(prime_fd(p), DMA_BUF_IOCTL_SYNC, &dbs);
+		if (r)
+			throw runtime_error("DMA_BUF_IOCTL_SYNC failed");
+	}
+}
+
+void DmabufFramebuffer::end_cpu_access()
+{
+	if (m_sync_flags == 0)
+		throw runtime_error("begin_cpu sync not started");
+
+	dma_buf_sync dbs {
+		.flags = DMA_BUF_SYNC_END | m_sync_flags
+	};
+
+	for (uint32_t p = 0; p < m_num_planes; ++p) {
+		int r = ioctl(prime_fd(p), DMA_BUF_IOCTL_SYNC, &dbs);
+		if (r)
+			throw runtime_error("DMA_BUF_IOCTL_SYNC failed");
+	}
+
+	m_sync_flags = 0;
+}
+
 }