On 02/14/2014 05:49 AM, Pawel Osciak wrote:
> On Thu, Feb 13, 2014 at 6:40 PM, Hans Verkuil <[email protected]> wrote:
>> From: Hans Verkuil <[email protected]>
>>
>> Commit 88e268702bfba78448abd20a31129458707383aa ("vb2: Improve file I/O
>> emulation to handle buffers in any order") broke read/write support if
>> the size of the buffer being read/written is less than the size of the
>> image.
>>
>> When the commit was tested originally I used qv4l2, which call read()
>> with exactly the size of the image. But if you try 'cat /dev/video0'
>> then it will fail and typically hang after reading two buffers.
>>
>> This patch fixes the behavior by adding a new buf_index field that
>> contains the index of the field currently being filled/read, or it
>> is num_buffers in which case a new buffer needs to be dequeued.
>>
>> Signed-off-by: Hans Verkuil <[email protected]>
>> Cc: Andy Walls <[email protected]>
>> ---
>> drivers/media/v4l2-core/videobuf2-core.c | 7 +++++--
>> 1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/media/v4l2-core/videobuf2-core.c
>> b/drivers/media/v4l2-core/videobuf2-core.c
>> index 7766bf5..a3b4b4c 100644
>> --- a/drivers/media/v4l2-core/videobuf2-core.c
>> +++ b/drivers/media/v4l2-core/videobuf2-core.c
>> @@ -2418,6 +2418,7 @@ struct vb2_fileio_data {
>> struct v4l2_requestbuffers req;
>> struct v4l2_buffer b;
>> struct vb2_fileio_buf bufs[VIDEO_MAX_FRAME];
>> + unsigned int buf_index;
>> unsigned int index;
>
> The two index fields are now confusing, especially because there is no
> documentation. Perhaps we could call index "cur_index" and also add
> documentation please?
I agree, I'll post an updated version today.
Regards,
Hans
>
>> unsigned int q_count;
>> unsigned int dq_count;
>> @@ -2519,6 +2520,7 @@ static int __vb2_init_fileio(struct vb2_queue *q, int
>> read)
>> fileio->bufs[i].queued = 1;
>> }
>> fileio->index = q->num_buffers;
>> + fileio->buf_index = q->num_buffers;
>> }
>>
>> /*
>> @@ -2597,7 +2599,7 @@ static size_t __vb2_perform_fileio(struct vb2_queue
>> *q, char __user *data, size_
>> /*
>> * Check if we need to dequeue the buffer.
>> */
>> - index = fileio->index;
>> + index = fileio->buf_index;
>> if (index >= q->num_buffers) {
>> /*
>> * Call vb2_dqbuf to get buffer back.
>> @@ -2611,7 +2613,7 @@ static size_t __vb2_perform_fileio(struct vb2_queue
>> *q, char __user *data, size_
>> return ret;
>> fileio->dq_count += 1;
>>
>> - index = fileio->b.index;
>> + fileio->buf_index = index = fileio->b.index;
>> buf = &fileio->bufs[index];
>>
>> /*
>> @@ -2689,6 +2691,7 @@ static size_t __vb2_perform_fileio(struct vb2_queue
>> *q, char __user *data, size_
>> fileio->q_count += 1;
>> if (fileio->index < q->num_buffers)
>> fileio->index++;
>> + fileio->buf_index = fileio->index;
>> }
>>
>> /*
>> --
>> 1.8.4.rc3
>>
>
>
>
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