From: "H. Willstrand" <h.willstrand@gmail.com>
To: Jiri Slaby <jirislaby@gmail.com>
Cc: video4linux-list@redhat.com,
v4l2 library <v4l2-library@linuxtv.org>,
Brandon Philips <bphilips@suse.de>,
SPCA50x Linux Device Driver Development
<spca50x-devs@lists.sourceforge.net>
Subject: Re: [V4l2-library] Messed up syscall return value
Date: Tue, 29 Jul 2008 00:35:20 +0200 [thread overview]
Message-ID: <1217284520.3371.2.camel@localhost.localdomain> (raw)
In-Reply-To: <488E46BC.10104@gmail.com>
Hi!
I think the memory allocation is wrong, you have NBUFFERS = 2 but
memset( ... ) only allocates for 1 buffer.
Regards,
H.Willstrand
On Tue, 2008-07-29 at 00:22 +0200, Jiri Slaby wrote:
> On 07/29/2008 12:16 AM, Gregor Jasny wrote:
> > ioctl(3, VIDIOC_REQBUFS or VT_DISALLOCATE, 0x7fffbfda0060) = 2
> >
> > Huh? Something evils seems to be going on in V4L2 land.
> > I've spotted the following lines in videobuf-core.c:videobuf_reqbufs
> >
> > req->count = retval;
> >
> > done:
> > mutex_unlock(&q->vb_lock);
> > return retval;
> >
> > That would explain the retval '2'. It seems a retval = 0; statement is missing here for the success case.
>
> Actually positive ioctl retval used to be often considered as OK in the past
> (and this approach is still used in few char drivers).
>
> But according to v4l docco, it isn't permitted here. Anyway I wouldn't place it
> in videobuf-core.c, but in vivi code; letting this decision on Mauro (CCed) ;).
>
> _______________________________________________
> V4L2-library mailing list
> V4L2-library@linuxtv.org
> http://www.linuxtv.org/cgi-bin/mailman/listinfo/v4l2-library
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next prev parent reply other threads:[~2008-07-28 22:36 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-07-23 12:20 Announcing libv4l 0.3.7 Hans de Goede
2008-07-28 21:49 ` Messed up syscall return value Gregor Jasny
[not found] ` <488E4090.5020600@gmail.com>
2008-07-28 22:16 ` [V4l2-library] " Gregor Jasny
[not found] ` <488E46BC.10104@gmail.com>
2008-07-28 22:34 ` Gregor Jasny
2008-07-28 22:35 ` H. Willstrand [this message]
2008-07-29 10:00 ` Hans de Goede
2008-07-29 11:52 ` Gregor Jasny
2008-07-29 19:49 ` Hans de Goede
2008-07-29 16:00 ` Mauro Carvalho Chehab
2008-07-29 19:05 ` Laurent Pinchart
2008-07-29 20:51 ` Mauro Carvalho Chehab
2008-07-29 20:57 ` Laurent Pinchart
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