From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934776AbbIVVKu (ORCPT ); Tue, 22 Sep 2015 17:10:50 -0400 Received: from nblzone-211-213.nblnetworks.fi ([83.145.211.213]:49855 "EHLO hillosipuli.retiisi.org.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1758878AbbIVVKt (ORCPT ); Tue, 22 Sep 2015 17:10:49 -0400 Date: Wed, 23 Sep 2015 00:10:15 +0300 From: Sakari Ailus To: Tiffany Lin Cc: Pawel Osciak , Marek Szyprowski , Kyungmin Park , Mauro Carvalho Chehab , Matthias Brugger , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, robin.murphy@arm.com, hverkuil@xs4all.nl Subject: Re: [RESEND PATCH] media: vb2: Fix vb2_dc_prepare do not correct sync data to device Message-ID: <20150922211015.GT3175@valkosipuli.retiisi.org.uk> References: <1442838371-21484-1-git-send-email-tiffany.lin@mediatek.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1442838371-21484-1-git-send-email-tiffany.lin@mediatek.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 Tiffany, (Robin and Hans cc'd.) On Mon, Sep 21, 2015 at 08:26:11PM +0800, Tiffany Lin wrote: > vb2_dc_prepare use the number of SG entries dma_map_sg_attrs return. > But in dma_sync_sg_for_device, it use lengths of each SG entries > before dma_map_sg_attrs. dma_map_sg_attrs will concatenate > SGs until dma length > dma seg bundary. sgt->nents will less than > sgt->orig_nents. Using SG entries after dma_map_sg_attrs > in vb2_dc_prepare will make some SGs are not sync to device. > After add DMA_ATTR_SKIP_CPU_SYNC in vb2_dc_get_userptr to remove > sync data to device twice. Device randomly get incorrect data because > some SGs are not sync to device. Change to use number of SG entries > before dma_map_sg_attrs in vb2_dc_prepare to prevent this issue. > > Signed-off-by: Tiffany Lin > --- > drivers/media/v4l2-core/videobuf2-dma-contig.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c b/drivers/media/v4l2-core/videobuf2-dma-contig.c > index 2397ceb..c5d00bd 100644 > --- a/drivers/media/v4l2-core/videobuf2-dma-contig.c > +++ b/drivers/media/v4l2-core/videobuf2-dma-contig.c > @@ -100,7 +100,7 @@ static void vb2_dc_prepare(void *buf_priv) > if (!sgt || buf->db_attach) > return; > > - dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir); > + dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir); > } > > static void vb2_dc_finish(void *buf_priv) > @@ -112,7 +112,7 @@ static void vb2_dc_finish(void *buf_priv) > if (!sgt || buf->db_attach) > return; > > - dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir); > + dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir); > } > > /*********************************************/ Acked-by: Sakari Ailus Could you post a similar patch for videobuf2-dma-sg as well, please? This should probably go to stable (since when?). videobuf-dma-sg appears to be broken, too, but the fix is more changes than one or two lines. -- Kind regards, Sakari Ailus e-mail: sakari.ailus@iki.fi XMPP: sailus@retiisi.org.uk