Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933458AbaGWUR2 (ORCPT ); Wed, 23 Jul 2014 16:17:28 -0400 Received: from mail-oa0-f54.google.com ([209.85.219.54]:56382 "EHLO mail-oa0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932847AbaGWUR1 (ORCPT ); Wed, 23 Jul 2014 16:17:27 -0400 MIME-Version: 1.0 In-Reply-To: References: Date: Wed, 23 Jul 2014 13:10:29 -0700 X-Google-Sender-Auth: B02Ye4HB2KsLWEKTlFIqppDDVrI Message-ID: Subject: Re: staging: Unwritten function for ion_carveout_heap.c From: Colin Cross To: Nick Krause Cc: Greg KH , John Stultz , Rebecca Zavin , Laura Abbott , gioh.kim@lge.com, benjamin.gaignard@linaro.org, "devel@driverdev.osuosl.org" , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 23, 2014 at 1:04 PM, Nick Krause wrote: > Hey Greg and others. > Sorry for another email but it seems the function, > ion_carveout_heap_unmap_dma is > just returning and not doing anything useful. Furthermore I am new so > I don't known how > to write this function but this may be causing some rather serious > bugs as if the dma heap > is not unmaped and we call this function a lot this will make the > kernel not able to handle dma requests > for this driver and other drivers that need this and in turn lead to > a oops or even a kernel panic due to leaked > dma allocated memory. I would recommend writing this function or > helping me write it in > other to avoid some rather serious bugs without a proper dma unmapping > function for this driver :). > Nick Look at ion_carveout_heap_map_dma - it doesn't do anything, it just returns a pre-existing virtual address. That means there is nothing to do in unmap. map_dma is actually a bit of a misnomer here, as the actual mapping is done in ion_map_dma_buf. All ion_carveout_heap_map_dma does is return the sg table for ion_map_dma_buf to pass to dma_map_sg. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/