On Fri, Oct 22, 2010 at 17:18, Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> wrote: > Em 06-09-2010 03:53, Marek Szyprowski escreveu: >> From: Pawel Osciak <p.osciak@xxxxxxxxxxx> >> >> VIDIOC_STREAMON should return EBUSY if streaming is already active. >> >> Signed-off-by: Pawel Osciak <p.osciak@xxxxxxxxxxx> >> Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx> >> Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> >> --- >> Documentation/DocBook/v4l/vidioc-streamon.xml | 7 +++++++ >> 1 files changed, 7 insertions(+), 0 deletions(-) >> >> diff --git a/Documentation/DocBook/v4l/vidioc-streamon.xml b/Documentation/DocBook/v4l/vidioc-streamon.xml >> index e42bff1..fdbd8d8 100644 >> --- a/Documentation/DocBook/v4l/vidioc-streamon.xml >> +++ b/Documentation/DocBook/v4l/vidioc-streamon.xml >> @@ -93,6 +93,13 @@ synchronize with other events.</para> >> been allocated (memory mapping) or enqueued (output) yet.</para> >> </listitem> >> </varlistentry> >> + <varlistentry> >> + <term><errorcode>EBUSY</errorcode></term> >> + <listitem> >> + <para><constant>VIDIOC_STREAMON</constant> called, but >> + streaming I/O already active.</para> >> + </listitem> >> + </varlistentry> >> </variablelist> >> </refsect1> >> </refentry> > > I'm in doubt about this patch. I don't see any problem on just return 0 if > stream is active. > > Actually, I think that this patch may break some applications, as there are > some cases where stream may start even without streamon (like via read() method). A quick grep over the media directory reveals that many drivers (including videobuf_streamon) return EBUSY for some cases. This patch was not intended to introduce something new to the API. I just wanted to document an undocumented return value. How should the EBUSY return be interpreted? Or should we get rid of it? -- Best regards, Pawel Osciak -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
