From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from perceval.ideasonboard.com ([95.142.166.194]:45274 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754641AbaDFXfW (ORCPT ); Sun, 6 Apr 2014 19:35:22 -0400 From: Laurent Pinchart To: "Scheuermann, Mail" Cc: "linux-media@vger.kernel.org" Subject: Re: AW: AW: v4l2_buffer with PBO mapped memory Date: Mon, 07 Apr 2014 01:37:28 +0200 Message-ID: <12148246.7IO9AkCti4@avalon> In-Reply-To: <67C778DDEF97AE4BA9DC4BA8ECFD811E1DB2EA13@KUUMEX11.barco.com> References: <533C2872.5090603@barco.com> <82154683.DEhQIaoLxb@avalon> <67C778DDEF97AE4BA9DC4BA8ECFD811E1DB2EA13@KUUMEX11.barco.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-media-owner@vger.kernel.org List-ID: Hi Thomas, On Friday 04 April 2014 20:01:33 Scheuermann, Mail wrote: > Hi Laurent, > > I've done the following: > > echo 3 >/sys/module/videobuf2_core/parameters/debug > > and found in /var/log/kern.log after starting my program: > > [239432.535077] vb2: Buffer 0, plane 0 offset 0x00000000 > [239432.535080] vb2: Buffer 1, plane 0 offset 0x001c2000 > [239432.535082] vb2: Buffer 2, plane 0 offset 0x00384000 > [239432.535083] vb2: Allocated 3 buffers, 1 plane(s) each > [239432.535085] vb2: qbuf: userspace address for plane 0 changed, > reacquiring memory > [239432.535087] vb2: qbuf: failed acquiring userspace memory for plane 0 This confirms everything is working properly up to the point where videobuf2- vmalloc fails to acquire the user pointer memory. The problem comes from vb2_vmalloc_get_userptr() in drivers/media/v4l2-core/videobuf2-vmalloc.c. Unfortunately that function lacks debugging. Are you familiar enough with kernel programming to add printk statements there and see where it fails ? > [239432.535088] vb2: qbuf: buffer preparation failed: -22 > [239432.535128] vb2: streamoff: not streaming -- Regards, Laurent Pinchart