media: vb2: Fix regression on poll() for RW mode

commit b93876845c5e30a92964eeb088d9d2e024118022 upstream.

When using a device is read/write mode, vb2 does not handle properly the
first select/poll operation.

The reason for this, is that when this code has been refactored, some of
the operations have changed their order, and now fileio emulator is not
started.

The reintroduced check to the core is enabled by a quirk flag, that
avoids this check by other subsystems like DVB.

Fixes: 49d8ab9feaf2 ("media] media: videobuf2: Separate vb2_poll()")
Reported-by: Dimitrios Katsaros <patcherwork@gmail.com>
Cc: Junghak Sung <jh1009.sung@samsung.com>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index ff8953ae52d142e654f30548d5ddf7bf08c45690..f1ed1467c0ce582957b8d1de9e2d0c2eec7d9ded 100644 (file)
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -2292,6 +2292,16 @@ unsigned int vb2_core_poll(struct vb2_queue *q, struct file *file,
        if (!vb2_is_streaming(q) || q->error)
                return POLLERR;
 
+       /*
+        * If this quirk is set and QBUF hasn't been called yet then
+        * return POLLERR as well. This only affects capture queues, output
+        * queues will always initialize waiting_for_buffers to false.
+        * This quirk is set by V4L2 for backwards compatibility reasons.
+        */
+       if (q->quirk_poll_must_check_waiting_for_buffers &&
+           q->waiting_for_buffers && (req_events & (POLLIN | POLLRDNORM)))
+               return POLLERR;
+
        /*
         * For output streams you can call write() as long as there are fewer
         * buffers queued than there are buffers available.

diff --git a/drivers/media/v4l2-core/videobuf2-v4l2.c b/drivers/media/v4l2-core/videobuf2-v4l2.c
index 91f552124050d2b3b91d2190af16fbdf2f9d7243..0b1b8c7b6ce51e69cd2c7f9e8c3eec7f6b6744eb 100644 (file)
--- a/drivers/media/v4l2-core/videobuf2-v4l2.c
+++ b/drivers/media/v4l2-core/videobuf2-v4l2.c
@@ -765,6 +765,12 @@ int vb2_queue_init(struct vb2_queue *q)
        q->is_output = V4L2_TYPE_IS_OUTPUT(q->type);
        q->copy_timestamp = (q->timestamp_flags & V4L2_BUF_FLAG_TIMESTAMP_MASK)
                        == V4L2_BUF_FLAG_TIMESTAMP_COPY;
+       /*
+        * For compatibility with vb1: if QBUF hasn't been called yet, then
+        * return POLLERR as well. This only affects capture queues, output
+        * queues will always initialize waiting_for_buffers to false.
+        */
+       q->quirk_poll_must_check_waiting_for_buffers = true;
 
        return vb2_core_queue_init(q);
 }
@@ -818,14 +824,6 @@ unsigned int vb2_poll(struct vb2_queue *q, struct file *file, poll_table *wait)
                        poll_wait(file, &fh->wait, wait);
        }
 
-       /*
-        * For compatibility with vb1: if QBUF hasn't been called yet, then
-        * return POLLERR as well. This only affects capture queues, output
-        * queues will always initialize waiting_for_buffers to false.
-        */
-       if (q->waiting_for_buffers && (req_events & (POLLIN | POLLRDNORM)))
-               return POLLERR;
-
        return res | vb2_core_poll(q, file, wait);
 }
 EXPORT_SYMBOL_GPL(vb2_poll);

diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index 8a0f55b6c2ba80e25c67caf89e2050fa58ae322f..3a1620946068ada2f3a3bd450dc115103f82c23c 100644 (file)
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -400,6 +400,9 @@ struct vb2_buf_ops {
  * @fileio_read_once:          report EOF after reading the first buffer
  * @fileio_write_immediately:  queue buffer after each write() call
  * @allow_zero_bytesused:      allow bytesused == 0 to be passed to the driver
+ * @quirk_poll_must_check_waiting_for_buffers: Return POLLERR at poll when QBUF
+ *              has not been called. This is a vb1 idiom that has been adopted
+ *              also by vb2.
  * @lock:      pointer to a mutex that protects the vb2_queue struct. The
  *             driver can set this to a mutex to let the v4l2 core serialize
  *             the queuing ioctls. If the driver wants to handle locking
@@ -463,6 +466,7 @@ struct vb2_queue {
        unsigned                        fileio_read_once:1;
        unsigned                        fileio_write_immediately:1;
        unsigned                        allow_zero_bytesused:1;
+       unsigned                   quirk_poll_must_check_waiting_for_buffers:1;
 
        struct mutex                    *lock;
        void                            *owner;