libv4l: Do not set format for control applications

From: Hans de Goede <hdegoede@redhat.com>

When we must do conversion (as we want todo flipping / processing) and
the cam does not default to a supported dest format, we set the emulated
format to rgb24, wait with doing this till the app actually does something
format related, otherwise control applications like v4l2ucp used to
become the stream owner locking out other apps.

Priority: normal

Signed-off-by: Hans de Goede <hdegoede@redhat.com>

1 files changed, 21 insertions, 9 deletions

diff --git a/v4l2-apps/libv4l/libv4l2/libv4l2.c b/v4l2-apps/libv4l/libv4l2/libv4l2.c
index fc5e63eaa..4f88ffd73 100644
--- a/v4l2-apps/libv4l/libv4l2/libv4l2.c
+++ b/v4l2-apps/libv4l/libv4l2/libv4l2.c
@@ -77,6 +77,7 @@
 #define V4L2_STREAM_CONTROLLED_BY_READ	0x0400
 #define V4L2_SUPPORTS_READ		0x0800
 #define V4L2_IS_UVC			0x1000
+#define V4L2_STREAM_TOUCHED		0x2000
 
 #define V4L2_MMAP_OFFSET_MAGIC      0xABCDEF00u
 
@@ -516,14 +517,6 @@ int v4l2_fd_open(int fd, int v4l2_flags)
 
   V4L2_LOG("open: %d\n", fd);
 
-  if (v4lconvert_supported_dst_fmt_only(convert) &&
-      !v4lconvert_supported_dst_format(fmt.fmt.pix.pixelformat)) {
-    V4L2_LOG("open %d: setting pixelformat to RGB24\n", fd);
-    fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_RGB24;
-    v4l2_ioctl(fd, VIDIOC_S_FMT, &fmt);
-    V4L2_LOG("open %d: done setting pixelformat\n", fd);
-  }
-
   return fd;
 }
 
@@ -746,8 +739,27 @@ int v4l2_ioctl (int fd, unsigned long int request, ...)
   }
 
 
-  if (stream_needs_locking)
+  if (stream_needs_locking) {
+    /* If this is the first stream related ioctl, and we should only allow
+       libv4lconvert supported destination formats (so that it can do flipping,
+       processing, etc.) and the current destination format is not supported,
+       try setting the format to RGB24 (which is a supported dest. format). */
+    if (!(devices[index].flags & V4L2_STREAM_TOUCHED) &&
+	!(devices[index].flags & V4L2_DISABLE_CONVERSION) &&
+	v4lconvert_supported_dst_fmt_only(devices[index].convert) &&
+	!v4lconvert_supported_dst_format(
+			      devices[index].dest_fmt.fmt.pix.pixelformat)) {
+      struct v4l2_format fmt = devices[index].dest_fmt;
+
+      V4L2_LOG("Setting pixelformat to RGB24 (supported_dst_fmt_only)");
+      devices[index].flags |= V4L2_STREAM_TOUCHED;
+      fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_RGB24;
+      v4l2_ioctl(fd, VIDIOC_S_FMT, &fmt);
+      V4L2_LOG("Done setting pixelformat (supported_dst_fmt_only)");
+    }
     pthread_mutex_lock(&devices[index].stream_lock);
+    devices[index].flags |= V4L2_STREAM_TOUCHED;
+  }
 
   converting = v4lconvert_needs_conversion(devices[index].convert,
 			 &devices[index].src_fmt, &devices[index].dest_fmt);