From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from osg.samsung.com ([64.30.133.232]:61383 "EHLO osg.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S967059AbeCAJsi (ORCPT ); Thu, 1 Mar 2018 04:48:38 -0500 Date: Thu, 1 Mar 2018 06:48:33 -0300 From: Mauro Carvalho Chehab To: Devin Heitmueller Cc: Linux Media Mailing List , Mauro Carvalho Chehab Subject: Re: [PATCH RFC] media: em28xx: don't use coherent buffer for DMA transfers Message-ID: <20180301064833.59eed81a@vento.lan> In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: Em Wed, 28 Feb 2018 09:49:12 -0500 Devin Heitmueller escreveu: > On Tue, Feb 27, 2018 at 12:42 PM, Mauro Carvalho Chehab > wrote: > > While coherent memory is cheap on x86, it has problems on > > arm. So, stop using it. > > > > Signed-off-by: Mauro Carvalho Chehab > > --- > > > > I wrote this patch in order to check if this would make things better > > for ISOCH transfers on Raspberry Pi3. It didn't. Yet, keep using > > coherent memory at USB drivers seem an overkill. > > > > So, I'm actually not sure if we should either go ahead and merge it > > or not. > > > > Comments? Tests? > > For what it's worth, while I haven't tested this patch you're > proposing, I've been running what is essentially the same change in a > private tree for several years in order for the device to work better > with several TI Davinci SOC platforms. Good to know! I guess then it is worth applying it. Btw, while here, I'm wandering if it should keep using URB_ISO_ASAP flag or not. On my tests, for DVB, it seems to be working both ways. Didn't test analog TV yet. Thanks, Mauro