From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from longford.logfs.org ([213.229.74.203]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1V76vH-0006sG-0k for linux-mtd@lists.infradead.org; Wed, 07 Aug 2013 16:49:20 +0000 Date: Wed, 7 Aug 2013 11:16:12 -0400 From: =?utf-8?B?SsO2cm4=?= Engel To: Jussi Kivilinna Subject: Re: [PATCH] alauda: do not use stack for URB transfer_buffers Message-ID: <20130807151612.GA18545@logfs.org> References: <20130806120329.8864.36301.stgit@localhost6.localdomain6> <20130806164913.GD10535@logfs.org> <5201E03D.30306@iki.fi> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <5201E03D.30306@iki.fi> Cc: David Woodhouse , linux-usb@vger.kernel.org, linux-mtd@lists.infradead.org List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 7 August 2013 08:50:53 +0300, Jussi Kivilinna wrote: > On 06.08.2013 19:49, Jörn Engel wrote: > > On Tue, 6 August 2013 15:03:29 +0300, Jussi Kivilinna wrote: > >> > >> Patch fixes alauda not to use stack as URB transfer_buffer. URB buffers need to > >> be DMA-able, which stack is not. > >> > >> Patch is only compile tested. > > > > I have tested the driver back when I wrote it. Not sure why it worked > > then, maybe the chip in my notebook back then didn't care about > > alignment or I just got lucky with the memory allocations. > > You might not see problems with your hardware/architecture. > > "Documentation/DMA-API-HOWTO.txt" discusses about "What memory is DMA'able?". Makes sense. I've read your patch over and it also makes sense. Acked-by: Joern Engel Jörn -- It's just what we asked for, but not what we want! -- anonymous