[for,v4l-utils] qv4l2: fix UVC support

Commit Message

Hans Verkuil March 13, 2010, 10:33 p.m. UTC

None

Patch

diff --git a/utils/qv4l2-qt4/general-tab.cpp b/utils/qv4l2-qt4/general-tab.cpp
index 50a3edc..706b15d 100644
--- a/utils/qv4l2-qt4/general-tab.cpp
+++ b/utils/qv4l2-qt4/general-tab.cpp
@@ -198,11 +198,23 @@  GeneralTab::GeneralTab(const QString &device, v4l2 &fd, int n, QWidget *parent)
 	if (m_querycap.capabilities & V4L2_CAP_STREAMING) {
 		v4l2_requestbuffers reqbuf;
 
-		if (reqbufs_user_cap(reqbuf, 1))
+		// Yuck. The videobuf framework does not accept a count of 0.
+		// This is out-of-spec, but it means that the only way to test which
+		// method is supported is to give it a non-zero count. But non-videobuf
+		// drivers like uvc do not allow e.g. S_FMT calls after a REQBUFS call
+		// with non-zero counts unless there is a REQBUFS call with count == 0
+		// in between. This is actual proper behavior, although somewhat
+		// unexpected. So the only way at the moment to do this that works
+		// everywhere is to call REQBUFS with a count of 1, and then again with
+	       	// a count of 0.
+		if (reqbufs_user_cap(reqbuf, 1)) {
 			m_capMethods->addItem("User pointer I/O", QVariant(methodUser));
-
-		if (reqbufs_mmap_cap(reqbuf, 1))
+			reqbufs_user_cap(reqbuf, 0);
+		}
+		if (reqbufs_mmap_cap(reqbuf, 1)) {
 			m_capMethods->addItem("Memory mapped I/O", QVariant(methodMmap));
+			reqbufs_mmap_cap(reqbuf, 0);
+		}
 	}
 	if (m_querycap.capabilities & V4L2_CAP_READWRITE) {
 		m_capMethods->addItem("read()", QVariant(methodRead));
diff --git a/utils/qv4l2-qt4/qv4l2.cpp b/utils/qv4l2-qt4/qv4l2.cpp
index 96cb4d7..63881be 100644
--- a/utils/qv4l2-qt4/qv4l2.cpp
+++ b/utils/qv4l2-qt4/qv4l2.cpp
@@ -352,7 +352,7 @@  void ApplicationWindow::stopCapture()
 			if (-1 == munmap(m_buffers[i].start, m_buffers[i].length))
 				perror("munmap");
 		// Free all buffers.
-		reqbufs_mmap_out(reqbufs, 0);
+		reqbufs_mmap_cap(reqbufs, 0);
 		break;
 
 	case methodUser:
@@ -360,6 +360,8 @@  void ApplicationWindow::stopCapture()
 			perror("VIDIOC_STREAMOFF");
 		for (i = 0; i < m_nbuffers; ++i)
 			free(m_buffers[i].start);
+		// Free all buffers.
+		reqbufs_user_cap(reqbufs, 0);
 		break;
 	}
 	free(m_buffers);