From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161528Ab2GLRoi (ORCPT ); Thu, 12 Jul 2012 13:44:38 -0400 Received: from mail-yw0-f46.google.com ([209.85.213.46]:62984 "EHLO mail-yw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161497Ab2GLRoY (ORCPT ); Thu, 12 Jul 2012 13:44:24 -0400 From: Rob Clark To: linux-kernel@vger.kernel.org Cc: patches@linaro.org, linaro-mm-sig@lists.linaro.org, Rob Clark Subject: [PATCH] device: add dma_params->max_segment_count Date: Thu, 12 Jul 2012 12:44:16 -0500 Message-Id: <1342115056-27419-1-git-send-email-rob.clark@linaro.org> X-Mailer: git-send-email 1.7.9.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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