Hi Mauro,
> As sparse complains:
> drivers/media/platform/timblogiw.c:562:22: warning: context imbalance in 'buffer_queue' - unexpected unlock
>
> there's something weird at the logic there. The semaphore seems
> to be protecting changes at the desc struct, however, the
> callback logic is not protected.
>
> Compile-tested only.
>
> Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxx>
> ---
> drivers/media/platform/timblogiw.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/media/platform/timblogiw.c b/drivers/media/platform/timblogiw.c
> index 113c9f3c0b3e..a5d2607cc396 100644
> --- a/drivers/media/platform/timblogiw.c
> +++ b/drivers/media/platform/timblogiw.c
> @@ -566,8 +566,8 @@ static void buffer_queue(struct videobuf_queue *vq, struct videobuf_buffer *vb)
> desc = dmaengine_prep_slave_sg(fh->chan,
> buf->sg, sg_elems, DMA_DEV_TO_MEM,
> DMA_PREP_INTERRUPT);
> + spin_lock_irq(&fh->queue_lock);
> if (!desc) {
> - spin_lock_irq(&fh->queue_lock);
> list_del_init(&vb->queue);
> vb->state = VIDEOBUF_PREPARED;
> return;
> @@ -576,8 +576,8 @@ static void buffer_queue(struct videobuf_queue *vq, struct videobuf_buffer *vb)
> desc->callback_param = buf;
> desc->callback = timblogiw_dma_cb;
>
> + spin_unlock_irq(&fh->queue_lock);
This is wrong: the videobuf core will take the queue_lock before calling buffer_queue,
so you are now locking it twice. (A pointer to queue_lock is passed in via
videobuf_queue_dma_contig_init()).
The sparse warning is because sparse doesn't know that the lock is taking when this
function is called, and it gets confused by the 'unlock - lock' sequence.
I've no idea how to tell sparse about that.
To be honest, as far as I am concerned the best approach would be to remove this
driver completely. It's for an old genivi devkit that's obsolete for a long time
now.
Regards,
Hans
> buf->cookie = desc->tx_submit(desc);
> -
> spin_lock_irq(&fh->queue_lock);
> }
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