From: Michael Jones <michael.jones@matrix-vision.de>
To: Linux Media Mailing List <linux-media@vger.kernel.org>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
Subject: buffer index when streaming user-ptr buffers
Date: Tue, 14 Jun 2011 17:50:13 +0200 [thread overview]
Message-ID: <4DF78335.80109@matrix-vision.de> (raw)
In the V4L2 spec, the description for v4l2_buffer.index says "This field
is only used for memory mapping I/O..."
However, in v4l-utils/contrib/capture-example.c, even user-pointer
buffers are indeed given a buf.index before being passed to VIDIOC_QBUF.
And at least in the OMAP ISP driver, this information is relied upon in
QBUF regardless of V4L2_MEMORY_MMAP/USERPTR. videobuf-core also uses
v4l2_buffer->index even if b->memory == V4L2_MEMORY_USERPTR.
Is this a bug in the OMAP driver and videobuf-core, and an unnecessary
assignment in capture-example? Or is the V4L2 spec out of touch/ out of
date?
-Michael
MATRIX VISION GmbH, Talstrasse 16, DE-71570 Oppenweiler
Registergericht: Amtsgericht Stuttgart, HRB 271090
Geschaeftsfuehrer: Gerhard Thullner, Werner Armingeon, Uwe Furtner
next reply other threads:[~2011-06-14 15:50 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-14 15:50 Michael Jones [this message]
2011-06-14 17:01 ` buffer index when streaming user-ptr buffers Laurent Pinchart
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