Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751539AbaDAMqP (ORCPT ); Tue, 1 Apr 2014 08:46:15 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:27122 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750786AbaDAMqO (ORCPT ); Tue, 1 Apr 2014 08:46:14 -0400 Date: Tue, 1 Apr 2014 08:46:06 -0400 From: Konrad Rzeszutek Wilk To: Jungseok Lee Cc: linux-kernel@vger.kernel.org, sungjinn.chung@samsung.com, linux-samsung-soc Subject: Re: [PATCH] swiotlb: Correct kernel command line handler Message-ID: <20140401124606.GA7135@phenom.dumpdata.com> References: <011801cf4d4c$f7ba51f0$e72ef5d0$@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <011801cf4d4c$f7ba51f0$e72ef5d0$@samsung.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Source-IP: ucsinet21.oracle.com [156.151.31.93] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 01, 2014 at 10:51:58AM +0900, Jungseok Lee wrote: > This patch corrects kernel command line handler when io_tlb_nslabs > is set to 0. > > A current implementation allocates default size memory (64MB) when > 0 is given to io_tlb_nslabs ("swiotlb=0") by kernel command line. > In other words, memory is allocated unintentionally. What are the other IOMMUs that end up taking over the DMA ops? Or do you end up with no DMA ops? > > Signed-off-by: Jungseok Lee > Signed-off-by: Sungjinn Chung > --- > lib/swiotlb.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/lib/swiotlb.c b/lib/swiotlb.c > index b604b83..9fe9f71 100644 > --- a/lib/swiotlb.c > +++ b/lib/swiotlb.c > @@ -55,6 +55,8 @@ > > int swiotlb_force; > > +static int swiotlb_no_use; > + > /* > * Used to do a quick range check in swiotlb_tbl_unmap_single and > * swiotlb_tbl_sync_single_*, to see if the memory was in fact allocated by this > @@ -102,6 +104,8 @@ setup_io_tlb_npages(char *str) > io_tlb_nslabs = simple_strtoul(str, &str, 0); > /* avoid tail segment of size < IO_TLB_SEGSIZE */ > io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE); > + if (!io_tlb_nslabs) > + swiotlb_no_use = 1; > } > if (*str == ',') > ++str; > @@ -212,7 +216,7 @@ swiotlb_init(int verbose) > unsigned char *vstart; > unsigned long bytes; > > - if (!io_tlb_nslabs) { > + if (!swiotlb_no_use && !io_tlb_nslabs) { > io_tlb_nslabs = (default_size >> IO_TLB_SHIFT); > io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE); > } > @@ -244,7 +248,7 @@ swiotlb_late_init_with_default_size(size_t default_size) > unsigned int order; > int rc = 0; > > - if (!io_tlb_nslabs) { > + if (!swiotlb_no_use && !io_tlb_nslabs) { > io_tlb_nslabs = (default_size >> IO_TLB_SHIFT); > io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE); > } > -- > 1.7.10.4 > > -- 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/