From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from lb1-smtp-cloud6.xs4all.net ([194.109.24.24]:47662 "EHLO lb1-smtp-cloud6.xs4all.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754877AbbGCKuS (ORCPT ); Fri, 3 Jul 2015 06:50:18 -0400 Message-ID: <559668BF.4020905@xs4all.nl> Date: Fri, 03 Jul 2015 12:49:35 +0200 From: Hans Verkuil MIME-Version: 1.0 To: Sakari Ailus , linux-media@vger.kernel.org CC: mchehab@osg.samsung.com Subject: Re: [PATCH 1/1] vb2: Only requeue buffers immediately once streaming is started References: <1435918810-21180-1-git-send-email-sakari.ailus@linux.intel.com> In-Reply-To: <1435918810-21180-1-git-send-email-sakari.ailus@linux.intel.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: On 07/03/2015 12:20 PM, Sakari Ailus wrote: > Buffers can be returned back to videobuf2 in driver's streamon handler. In > this case vb2_buffer_done() with buffer state VB2_BUF_STATE_QUEUED will > cause the driver's buf_queue vb2 operation to be called, queueing the same > buffer again only to be returned to videobuf2 using vb2_buffer_done() and so > on. > > Instead of using q->start_streamin_called to judge whether to return the > buffer to the driver immediately, use q->streaming which is set only after > the driver's start_streaming() vb2 operation is called. I don't think this patch will work. If q->min_buffers_needed is > 0, then q->streaming and q->start_streaming_called will both be true in vb2_buffer_done(), still causing the same issue. The problem is that there is no clear distinction between STATE_QUEUED as used in start_streaming and STATE_QUEUED as used to requeue a buffer while streaming. The best option here I think is to introduce a STATE_REQUEUE for the second use case. Regards, Hans > > Fixes: ce0eff016f72 ("[media] vb2: allow requeuing buffers while streaming") > Signed-off-by: Sakari Ailus > Cc: stable@vger.kernel.org # for v4.1 > --- > drivers/media/v4l2-core/videobuf2-core.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c > index 1a096a6..6957078 100644 > --- a/drivers/media/v4l2-core/videobuf2-core.c > +++ b/drivers/media/v4l2-core/videobuf2-core.c > @@ -1208,7 +1208,7 @@ void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state) > spin_unlock_irqrestore(&q->done_lock, flags); > > if (state == VB2_BUF_STATE_QUEUED) { > - if (q->start_streaming_called) > + if (q->streaming) > __enqueue_in_driver(vb); > return; > } >