media: vb2: Fix a bug about unnecessary calls to queue cancel and free

Currently, there's a logic with checks if *count is non-zero,
q->num_buffers is zero and q->memory is different than memory.

That's flawed when the device is initialized, or after the
queues are freed, as it does, unnecessary calls to
__vb2_queue_cancel() and  __vb2_queue_free().

That can be avoided by making sure that q->memory is set to
VB2_MEMORY_UNKNOWN at vb2_core_queue_init(), and adding such
check at the loop.

[mchehab@s-opensource.com: fix checkpatch issues and improve the
 patch, by setting q->memory to zero at vb2_core_queue_init]

Signed-off-by: Satendra Singh Thakur <satendra.t@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

diff --git a/drivers/media/common/videobuf/videobuf2-core.c b/drivers/media/common/videobuf/videobuf2-core.c
index 365b30c..9406d7b 100644 (file)
--- a/drivers/media/common/videobuf/videobuf2-core.c
+++ b/drivers/media/common/videobuf/videobuf2-core.c
@@ -524,7 +524,7 @@ static int __vb2_queue_free(struct vb2_queue *q, unsigned int buffers)
 
        q->num_buffers -= buffers;
        if (!q->num_buffers) {
-               q->memory = 0;
+               q->memory = VB2_MEMORY_UNKNOWN;
                INIT_LIST_HEAD(&q->queued_list);
        }
        return 0;
@@ -666,7 +666,8 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
                return -EBUSY;
        }
 
-       if (*count == 0 || q->num_buffers != 0 || q->memory != memory) {
+       if (*count == 0 || q->num_buffers != 0 ||
+           (q->memory != VB2_MEMORY_UNKNOWN && q->memory != memory)) {
                /*
                 * We already have buffers allocated, so first check if they
                 * are not in use and can be freed.
@@ -1999,6 +2000,8 @@ int vb2_core_queue_init(struct vb2_queue *q)
        mutex_init(&q->mmap_lock);
        init_waitqueue_head(&q->done_wq);
 
+       q->memory = VB2_MEMORY_UNKNOWN;
+
        if (q->buf_struct_size == 0)
                q->buf_struct_size = sizeof(struct vb2_buffer);