Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932212AbcJLCTX (ORCPT ); Tue, 11 Oct 2016 22:19:23 -0400 Received: from ec2-52-27-115-49.us-west-2.compute.amazonaws.com ([52.27.115.49]:46247 "EHLO s-opensource.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752209AbcJLCTV (ORCPT ); Tue, 11 Oct 2016 22:19:21 -0400 Date: Tue, 11 Oct 2016 23:19:13 -0300 From: Mauro Carvalho Chehab To: Kosuke Tatsukawa Cc: Linux Media Mailing List , "Mauro Carvalho Chehab" , Mauro Carvalho Chehab , Andy Lutomirski , "Johannes Stezenbach" , Jiri Kosina , "Patrick Boettcher" , Linux Kernel Mailing List , Andy Lutomirski , "Michael Krufky" , Mauro Carvalho Chehab , "jrg.otte@gmail.com" , Hans Verkuil , Wolfram Sang Subject: Re: [PATCH v2 28/31] cpia2_usb: don't use stack for DMA Message-ID: <20161011231913.4c3df3d4@vento.lan> In-Reply-To: <17EC94B0A072C34B8DCF0D30AD16044A028EFC0B@BPXM09GP.gisp.nec.co.jp> References: <17EC94B0A072C34B8DCF0D30AD16044A028EFC0B@BPXM09GP.gisp.nec.co.jp> Organization: Samsung X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.31; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1768 Lines: 53 Em Tue, 11 Oct 2016 22:56:06 +0000 Kosuke Tatsukawa escreveu: > Hi, > > > The USB control messages require DMA to work. We cannot pass > > a stack-allocated buffer, as it is not warranted that the > > stack would be into a DMA enabled area. > > > > Signed-off-by: Mauro Carvalho Chehab > > Signed-off-by: Mauro Carvalho Chehab > > --- > > drivers/media/usb/cpia2/cpia2_usb.c | 32 +++++++++++++++++++++++++++++--- > > 1 file changed, 29 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/media/usb/cpia2/cpia2_usb.c b/drivers/media/usb/cpia2/cpia2_usb.c > > index 13620cdf0599..417d683b237d 100644 > > --- a/drivers/media/usb/cpia2/cpia2_usb.c > > +++ b/drivers/media/usb/cpia2/cpia2_usb.c > > @@ -545,10 +545,19 @@ static void free_sbufs(struct camera_data *cam) > > static int write_packet(struct usb_device *udev, > > u8 request, u8 * registers, u16 start, size_t size) > > { > > + unsigned char *buf; > > + int ret; > > + > > if (!registers || size <= 0) > > return -EINVAL; > > > > - return usb_control_msg(udev, > > + buf = kmalloc(size, GFP_KERNEL); > > + if (!buf) > > + return -ENOMEM; > > + > > + memcpy(buf, registers, size); > > + > > + ret = usb_control_msg(udev, > > usb_sndctrlpipe(udev, 0), > > request, > > USB_TYPE_VENDOR | USB_RECIP_DEVICE, > > @@ -557,6 +566,9 @@ static int write_packet(struct usb_device *udev, > > registers, /* buffer */ > ========= > > I think you also want to change the argument to usb_control_msg() from > "registers" to "buf" in write_packet(). True! Thanks for pointing it! Just sent a version of the patch with this fixed. Regards, Mauro