From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-ey0-f174.google.com ([209.85.215.174]:46926 "EHLO mail-ey0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754361Ab2BBXGM (ORCPT ); Thu, 2 Feb 2012 18:06:12 -0500 Received: by eaah12 with SMTP id h12so1242831eaa.19 for ; Thu, 02 Feb 2012 15:06:10 -0800 (PST) Message-ID: <4F2B16DF.3040400@gmail.com> Date: Fri, 03 Feb 2012 00:06:07 +0100 From: Gianluca Gennari Reply-To: gennarone@gmail.com MIME-Version: 1.0 To: Devin Heitmueller CC: Andy Furniss , linux-media@vger.kernel.org Subject: Re: PCTV 290e page allocation failure References: <4F2AC7BF.4040006@ukfsn.org> <4F2ADDCB.4060200@gmail.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: Il 02/02/2012 20:07, Devin Heitmueller ha scritto: > On Thu, Feb 2, 2012 at 2:02 PM, Gianluca Gennari wrote: >> I'm trying to reproduce the problem with another em28xx-dvb device to >> see if it is not restricted to the PCTV 290e. Before the PCTV 290e, I >> was using a different device with a driver based on the dvb-usb >> framework, and I never observed similar crashes. > > On ARM based platforms it is very likely you will run into this issue > with most USB based tuners. It's because over time there is memory > fragmentation that occurs which prevents being able to allocate large > enough chunks of coherent memory. > > Making such a scenario work would require hacks to the driver code to > preallocate the memory in some form of static pool at system boot (or > perhaps at driver initialization), and then reuse that memory instead > of attempting to allocate it as needed. > > Devin > Hi Devin, thanks for the explanation. The CPU is MIPS based (not ARM) but I guess there is not much of a difference from this point of view. As I mentioned in my first reply, I never had this kind of errors when I was using a dvb-usb USB stick. Now I'm trying to replicate the problem with a Terratec Hybrid XS (em28xx-dvb + zl10353 + xc2028), and so far I've stressed it for a few hours without problems. We will see in a day or two if I can make it fail in the same way. Regards, Gianluca