From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx113.postini.com [74.125.245.113]) by kanga.kvack.org (Postfix) with SMTP id 81B7F6B004D for ; Fri, 20 Jul 2012 02:21:10 -0400 (EDT) Received: from epcpsbgm2.samsung.com (mailout4.samsung.com [203.254.224.34]) by mailout4.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0M7G00A2I4B87Q00@mailout4.samsung.com> for linux-mm@kvack.org; Fri, 20 Jul 2012 15:21:08 +0900 (KST) Received: from AMDC159 ([106.116.147.30]) by mmp2.samsung.com (Oracle Communications Messaging Server 7u4-24.01 (7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTPA id <0M7G00L714AS2470@mmp2.samsung.com> for linux-mm@kvack.org; Fri, 20 Jul 2012 15:21:08 +0900 (KST) From: Marek Szyprowski References: <1342715014-5316-1-git-send-email-rob.clark@linaro.org> <1342715014-5316-2-git-send-email-rob.clark@linaro.org> In-reply-to: <1342715014-5316-2-git-send-email-rob.clark@linaro.org> Subject: RE: [PATCH 1/2] device: add dma_params->max_segment_count Date: Fri, 20 Jul 2012 08:20:50 +0200 Message-id: <018b01cd663f$d3a23c10$7ae6b430$%szyprowski@samsung.com> MIME-version: 1.0 Content-type: text/plain; charset=us-ascii Content-transfer-encoding: 7bit Content-language: pl Sender: owner-linux-mm@kvack.org List-ID: To: 'Rob Clark' , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linaro-mm-sig@lists.linaro.org, dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org Cc: patches@linaro.org, linux@arm.linux.org.uk, arnd@arndb.de, jesse.barker@linaro.org, daniel@ffwll.ch, Tomasz Stanislawski , sumit.semwal@ti.com, maarten.lankhorst@canonical.com, 'Rob Clark' Hello, On Thursday, July 19, 2012 6:24 PM Rob Clark wrote: > From: Rob Clark > > For devices which have constraints about maximum number of segments > in an sglist. For example, a device which could only deal with > contiguous buffers would set max_segment_count to 1. > > The initial motivation is for devices sharing buffers via dma-buf, > to allow the buffer exporter to know the constraints of other > devices which have attached to the buffer. The dma_mask and fields > in 'struct device_dma_parameters' tell the exporter everything else > that is needed, except whether the importer has constraints about > maximum number of segments. > > Signed-off-by: Rob Clark Yea, it is a really good idea to add this to struct device_dma_parameters. We only need to initialize it to '1' in platform startup code for all devices relevant to buffer sharing. Acked-by: Marek Szyprowski > --- > include/linux/device.h | 1 + > include/linux/dma-mapping.h | 16 ++++++++++++++++ > 2 files changed, 17 insertions(+) > > diff --git a/include/linux/device.h b/include/linux/device.h > index 161d962..3813735 100644 > --- a/include/linux/device.h > +++ b/include/linux/device.h > @@ -568,6 +568,7 @@ struct device_dma_parameters { > * sg limitations. > */ > unsigned int max_segment_size; > + unsigned int max_segment_count; /* zero for unlimited */ > unsigned long segment_boundary_mask; > }; > > diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h > index dfc099e..f380f79 100644 > --- a/include/linux/dma-mapping.h > +++ b/include/linux/dma-mapping.h > @@ -111,6 +111,22 @@ static inline unsigned int dma_set_max_seg_size(struct device *dev, > return -EIO; > } > > +static inline unsigned int dma_get_max_seg_count(struct device *dev) > +{ > + return dev->dma_parms ? dev->dma_parms->max_segment_count : 0; > +} > + > +static inline int dma_set_max_seg_count(struct device *dev, > + unsigned int count) > +{ > + if (dev->dma_parms) { > + dev->dma_parms->max_segment_count = count; > + return 0; > + } else > + return -EIO; > +} > + > + > static inline unsigned long dma_get_seg_boundary(struct device *dev) > { > return dev->dma_parms ? > -- > 1.7.9.5 Best regards -- Marek Szyprowski Samsung Poland R&D Center -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org