From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-qg0-f66.google.com ([209.85.192.66]:35636 "EHLO mail-qg0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754697AbcFPRn3 (ORCPT ); Thu, 16 Jun 2016 13:43:29 -0400 Received: by mail-qg0-f66.google.com with SMTP id t106so4357542qgt.2 for ; Thu, 16 Jun 2016 10:43:29 -0700 (PDT) Message-ID: <1466099005.11108.15.camel@gmail.com> Subject: Re: [PATCH 00/38] i.MX5/6 Video Capture From: Nicolas Dufresne Reply-To: nicolas@ndufresne.ca To: Steve Longerbeam , Jack Mitchell , Steve Longerbeam , linux-media@vger.kernel.org Date: Thu, 16 Jun 2016 13:43:25 -0400 In-Reply-To: <5762DB8A.8090906@mentor.com> References: <1465944574-15745-1-git-send-email-steve_longerbeam@mentor.com> <64c29bbc-2273-2a9d-3059-ab8f62dc531b@embed.me.uk> <576202D0.6010608@mentor.com> <597d73df-0fa0-fa8d-e0e5-0ad8b2c49bcf@embed.me.uk> <5762DB8A.8090906@mentor.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-media-owner@vger.kernel.org List-ID: Le jeudi 16 juin 2016 à 10:02 -0700, Steve Longerbeam a écrit : > I found the cause at least in my case. After enabling dynamic debug in > videobuf2-dma-contig.c, "v4l2-ctl -d/dev/video0 --stream-user=8" gives > me > > [  468.826046] user data must be aligned to 64 bytes > > > > But even getting past that alignment issue, I've only tested userptr (in mem2mem > driver) by giving the driver a user address of a mmap'ed kernel contiguous > buffer. A true discontiguous user buffer may not work, the IPU DMA does not > support scatter-gather. If it's dma-contig, you'll need page aligned and contiguous memory. What some test application do when testing their driver with that, is to allocate memory using another device, or m2m device, that uses the same allocator. regards, Nicolas