From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753620AbcJUHtY (ORCPT ); Fri, 21 Oct 2016 03:49:24 -0400 Received: from nblzone-211-213.nblnetworks.fi ([83.145.211.213]:48032 "EHLO hillosipuli.retiisi.org.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751839AbcJUHtX (ORCPT ); Fri, 21 Oct 2016 03:49:23 -0400 Date: Fri, 21 Oct 2016 10:48:45 +0300 From: Sakari Ailus To: Thierry Escande Cc: Mauro Carvalho Chehab , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, Pawel Osciak , Marek Szyprowski , Kyungmin Park Subject: Re: [PATCH v3] [media] vb2: Add support for capture_dma_bidirectional queue flag Message-ID: <20161021074845.GZ9460@valkosipuli.retiisi.org.uk> References: <1477034705-5829-1-git-send-email-thierry.escande@collabora.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1477034705-5829-1-git-send-email-thierry.escande@collabora.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Thierry, On Fri, Oct 21, 2016 at 09:25:05AM +0200, Thierry Escande wrote: > From: Pawel Osciak > > When this flag is set for CAPTURE queues by the driver on calling > vb2_queue_init(), it forces the buffers on the queue to be > allocated/mapped with DMA_BIDIRECTIONAL direction flag instead of > DMA_FROM_DEVICE. This allows the device not only to write to the > buffers, but also read out from them. This may be useful e.g. for codec > hardware which may be using CAPTURE buffers as reference to decode > other buffers. > > This flag is ignored for OUTPUT queues as we don't want to allow HW to > be able to write to OUTPUT buffers. > > Signed-off-by: Pawel Osciak > Tested-by: Pawel Osciak > Signed-off-by: Thierry Escande > > diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c > index 21900202..22d6105 100644 > --- a/drivers/media/v4l2-core/videobuf2-core.c > +++ b/drivers/media/v4l2-core/videobuf2-core.c > @@ -194,8 +194,7 @@ static void __enqueue_in_driver(struct vb2_buffer *vb); > static int __vb2_buf_mem_alloc(struct vb2_buffer *vb) > { > struct vb2_queue *q = vb->vb2_queue; > - enum dma_data_direction dma_dir = > - q->is_output ? DMA_TO_DEVICE : DMA_FROM_DEVICE; > + enum dma_data_direction dma_dir = VB2_DMA_DIR(q); > void *mem_priv; > int plane; > int ret = -ENOMEM; > @@ -978,8 +977,7 @@ static int __qbuf_userptr(struct vb2_buffer *vb, const void *pb) > void *mem_priv; > unsigned int plane; > int ret = 0; > - enum dma_data_direction dma_dir = > - q->is_output ? DMA_TO_DEVICE : DMA_FROM_DEVICE; > + enum dma_data_direction dma_dir = VB2_DMA_DIR(q); > bool reacquired = vb->planes[0].mem_priv == NULL; > > memset(planes, 0, sizeof(planes[0]) * vb->num_planes); > @@ -1096,8 +1094,7 @@ static int __qbuf_dmabuf(struct vb2_buffer *vb, const void *pb) > void *mem_priv; > unsigned int plane; > int ret = 0; > - enum dma_data_direction dma_dir = > - q->is_output ? DMA_TO_DEVICE : DMA_FROM_DEVICE; > + enum dma_data_direction dma_dir = VB2_DMA_DIR(q); > bool reacquired = vb->planes[0].mem_priv == NULL; > > memset(planes, 0, sizeof(planes[0]) * vb->num_planes); Please also check where dma_dir is being used especially in memory type implementation. There are several comparisons to DMA_FROM_DEVICE which will have a different result if DMA_BIDIRECTIONAL is used instead. -- Sakari Ailus e-mail: sakari.ailus@iki.fi XMPP: sailus@retiisi.org.uk