Return-path: Received: from charlotte.tuxdriver.com ([70.61.120.58]:48305 "EHLO smtp.tuxdriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755891Ab0JYOaN (ORCPT ); Mon, 25 Oct 2010 10:30:13 -0400 Date: Mon, 25 Oct 2010 10:22:32 -0400 From: "John W. Linville" To: Hin-Tak Leung Cc: Larry Finger , Serafeim Zanikolas , herton@mandriva.com.br, joe@perches.com, davem@davemloft.net, linux-wireless@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] drivers: rtl818x: request DMA-able memory Message-ID: <20101025142232.GC2414@tuxdriver.com> References: <1287952327-9924-1-git-send-email-sez@debian.org> <4CC5851D.1040204@lwfinger.net> <4CC5900A.2050209@users.sourceforge.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <4CC5900A.2050209@users.sourceforge.net> Sender: linux-wireless-owner@vger.kernel.org List-ID: On Mon, Oct 25, 2010 at 03:11:22PM +0100, Hin-Tak Leung wrote: > > > Larry Finger wrote: > >On 10/24/2010 03:32 PM, Serafeim Zanikolas wrote: > >>Despite the indicated intention in comment, the kmalloc() call was not > >>explicitly requesting memory from ZONE_DMA. > >> > >>Signed-off-by: Serafeim Zanikolas > >>--- > >> drivers/net/wireless/rtl818x/rtl8187_dev.c | 3 ++- > >> 1 files changed, 2 insertions(+), 1 deletions(-) > >> > >>diff --git a/drivers/net/wireless/rtl818x/rtl8187_dev.c b/drivers/net/wireless/rtl818x/rtl8187_dev.c > >>index 38fa824..771794d 100644 > >>--- a/drivers/net/wireless/rtl818x/rtl8187_dev.c > >>+++ b/drivers/net/wireless/rtl818x/rtl8187_dev.c > >>@@ -1343,7 +1343,8 @@ static int __devinit rtl8187_probe(struct usb_interface *intf, > >> priv->is_rtl8187b = (id->driver_info == DEVICE_RTL8187B); > >> /* allocate "DMA aware" buffer for register accesses */ > >>- priv->io_dmabuf = kmalloc(sizeof(*priv->io_dmabuf), GFP_KERNEL); > >>+ priv->io_dmabuf = kmalloc(sizeof(*priv->io_dmabuf), > >>+ GFP_DMA | GFP_KERNEL); > >> if (!priv->io_dmabuf) { > >> err = -ENOMEM; > >> goto err_free_dev; > > > >ACK. > > > >Larry > > Acked-by: Hin-Tak Leung > > I had a quick look for similiar constructs and AFAIK only the > b43/b43legacy drivers uses DMA buffers. Seems to be a rare practice. > Is that something we should or should not do? It doesn't mean what you think it means. It is a relic of the past, used to indicate memory below 16MB so that ISA devices could do DMA. John -- John W. Linville Someday the world will need a hero, and you linville@tuxdriver.com might be all we have. Be ready.