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Message-ID: <CAPybu_0-b2BfuTVd09B4dreFHCsYSg=SjjrDCHXKrqNGzFSX2w@mail.gmail.com>
Date: Tue, 8 Oct 2013 09:58:23 +0200
From: Ricardo Ribalda Delgado <ricardo.ribalda@...il.com>
To: Marek Szyprowski <m.szyprowski@...sung.com>
Cc: Pawel Osciak <pawel@...iak.com>,
Kyungmin Park <kyungmin.park@...sung.com>,
Mauro Carvalho Chehab <m.chehab@...sung.com>,
linux-media <linux-media@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] vb2: Allow STREAMOFF for io emulator
Hi Marek
Thanks for your comments. I was just trying to find a way to stop
streaming while in read/write mode without having to close the
descriptor. I thought reusing streamoff was more clever than creating
a new ioctl.
Thanks!
On Tue, Oct 8, 2013 at 9:22 AM, Marek Szyprowski
<m.szyprowski@...sung.com> wrote:
> Hello,
>
>
> On 2013-10-04 15:49, Ricardo Ribalda Delgado wrote:
>>
>> A video device opened and streaming in io emulator mode can only stop
>> streamming if its file descriptor is closed.
>>
>> There are some parameters that can only be changed if the device is not
>> streaming. Also, the power consumption of a device streaming could be
>> different than one not streaming.
>>
>> With this patch a video device opened in io emulator can be stopped on
>> demand.
>>
>> Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@...il.com>
>
>
> Read/write-based io mode must not be mixed with ioctrl-based IO, so I really
> cannot accept this patch. Check V4L2 documentation for more details.
>
>
>> ---
>> drivers/media/v4l2-core/videobuf2-core.c | 11 ++++++-----
>> 1 file changed, 6 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/media/v4l2-core/videobuf2-core.c
>> b/drivers/media/v4l2-core/videobuf2-core.c
>> index 9fc4bab..097fba8 100644
>> --- a/drivers/media/v4l2-core/videobuf2-core.c
>> +++ b/drivers/media/v4l2-core/videobuf2-core.c
>> @@ -1686,6 +1686,7 @@ int vb2_streamon(struct vb2_queue *q, enum
>> v4l2_buf_type type)
>> }
>> EXPORT_SYMBOL_GPL(vb2_streamon);
>> +static int __vb2_cleanup_fileio(struct vb2_queue *q);
>> /**
>> * vb2_streamoff - stop streaming
>> @@ -1704,11 +1705,6 @@ EXPORT_SYMBOL_GPL(vb2_streamon);
>> */
>> int vb2_streamoff(struct vb2_queue *q, enum v4l2_buf_type type)
>> {
>> - if (q->fileio) {
>> - dprintk(1, "streamoff: file io in progress\n");
>> - return -EBUSY;
>> - }
>> -
>> if (type != q->type) {
>> dprintk(1, "streamoff: invalid stream type\n");
>> return -EINVAL;
>> @@ -1719,6 +1715,11 @@ int vb2_streamoff(struct vb2_queue *q, enum
>> v4l2_buf_type type)
>> return -EINVAL;
>> }
>> + if (q->fileio) {
>> + __vb2_cleanup_fileio(q);
>> + return 0;
>> + }
>> +
>> /*
>> * Cancel will pause streaming and remove all buffers from the
>> driver
>> * and videobuf, effectively returning control over them to
>> userspace.
>
>
> Best regards
> --
> Marek Szyprowski
> Samsung R&D Institute Poland
>
--
Ricardo Ribalda
--
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