From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932177AbcFTKUq (ORCPT ); Mon, 20 Jun 2016 06:20:46 -0400 Received: from lb3-smtp-cloud2.xs4all.net ([194.109.24.29]:55886 "EHLO lb3-smtp-cloud2.xs4all.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753459AbcFTKUi (ORCPT ); Mon, 20 Jun 2016 06:20:38 -0400 Subject: Re: [PATCH] vb2: V4L2_BUF_FLAG_DONE is set after DQBUF To: Ricardo Ribalda Delgado References: <1466413304-8328-1-git-send-email-ricardo.ribalda@gmail.com> <5767BD2F.5070205@xs4all.nl> Cc: Pawel Osciak , Marek Szyprowski , Kyungmin Park , Mauro Carvalho Chehab , linux-media , LKML , Hans Verkuil , Dimitrios Katsaros From: Hans Verkuil Message-ID: <5767C2B4.6010908@xs4all.nl> Date: Mon, 20 Jun 2016 12:17:24 +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: Content-Type: text/plain; charset=utf-8 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 12:12 PM, Ricardo Ribalda Delgado wrote: > Good catch :) > > I will prepare the new version. Btw, can I also merge > vb2_internal_dqbuf and vb2_dqbuf in one function? Seems a bit > overkilled that split. No, that's not possible. vb2_internal_dqbuf is used in the threading code to implement read() and vb2_fileio_is_active() returns true in that case. > > Regarding v42l_compliance... I can take care of that if you dare :) It would be great if you can add a test for this. Regards, Hans > > Best regards! > > On Mon, Jun 20, 2016 at 11:53 AM, Hans Verkuil wrote: >> 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); >>> >>> > > >