From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754074AbcFTJ4E (ORCPT ); Mon, 20 Jun 2016 05:56:04 -0400 Received: from lb1-smtp-cloud2.xs4all.net ([194.109.24.21]:37704 "EHLO lb1-smtp-cloud2.xs4all.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752020AbcFTJ4C (ORCPT ); Mon, 20 Jun 2016 05:56:02 -0400 Subject: Re: [PATCH] vb2: V4L2_BUF_FLAG_DONE is set after DQBUF To: Ricardo Ribalda Delgado , Pawel Osciak , Marek Szyprowski , Kyungmin Park , Mauro Carvalho Chehab , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, hans.verkuil@cisco.com, Dimitrios Katsaros References: <1466413304-8328-1-git-send-email-ricardo.ribalda@gmail.com> From: Hans Verkuil Message-ID: <5767BD2F.5070205@xs4all.nl> Date: Mon, 20 Jun 2016 11:53:51 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Icedove/38.7.2 MIME-Version: 1.0 In-Reply-To: <1466413304-8328-1-git-send-email-ricardo.ribalda@gmail.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/20/2016 11:01 AM, Ricardo Ribalda Delgado wrote: > According to the doc, V4L2_BUF_FLAG_DONE is cleared after DQBUF: > > V4L2_BUF_FLAG_DONE 0x00000004 ... After calling the VIDIOC_QBUF or > VIDIOC_DQBUF it is always cleared ... > > Unfortunately, it seems that videobuf2 keeps it set after DQBUF. This > can be tested with vivid and dev_debug: > > [257604.338082] video1: VIDIOC_DQBUF: 71:33:25.00260479 index=3, > type=vid-cap, flags=0x00002004, field=none, sequence=163, > memory=userptr, bytesused=460800, offset/userptr=0x344b000, > length=460800 > > This patch changes the order when fill_user_buffer() is called, > to follow the documentation. > > Reported-by: Dimitrios Katsaros > Signed-off-by: Ricardo Ribalda Delgado Sorry, this won't work. Calling __vb2_dqbuf will overwrite the state VB2_BUF_STATE_ERROR and so the V4L2_BUF_FLAG_ERROR flag will never be set. The same is true for the last 'if' in the __fill_v4l2_buffer() function. I think it might be better to keep this code and instead change the vb2_internal_dqbuf function to just clear the DONE flag after calling vb2_core_dqbuf. It would be nice to have a v4l2_compliance check for this as well. Regards, Hans > --- > drivers/media/v4l2-core/videobuf2-core.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c > index 633fc1ab1d7a..63981f28075e 100644 > --- a/drivers/media/v4l2-core/videobuf2-core.c > +++ b/drivers/media/v4l2-core/videobuf2-core.c > @@ -1771,10 +1771,6 @@ int vb2_core_dqbuf(struct vb2_queue *q, unsigned int *pindex, void *pb, > if (pindex) > *pindex = vb->index; > > - /* Fill buffer information for the userspace */ > - if (pb) > - call_void_bufop(q, fill_user_buffer, vb, pb); > - > /* Remove from videobuf queue */ > list_del(&vb->queued_entry); > q->queued_count--; > @@ -1784,6 +1780,10 @@ int vb2_core_dqbuf(struct vb2_queue *q, unsigned int *pindex, void *pb, > /* go back to dequeued state */ > __vb2_dqbuf(vb); > > + /* Fill buffer information for the userspace */ > + if (pb) > + call_void_bufop(q, fill_user_buffer, vb, pb); > + > dprintk(1, "dqbuf of buffer %d, with state %d\n", > vb->index, vb->state); > >