From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752508AbcFNP73 (ORCPT ); Tue, 14 Jun 2016 11:59:29 -0400 Received: from mga03.intel.com ([134.134.136.65]:7011 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752449AbcFNP72 (ORCPT ); Tue, 14 Jun 2016 11:59:28 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.26,471,1459839600"; d="scan'208";a="1001766706" Message-ID: <1465920046.30123.83.camel@linux.intel.com> Subject: Re: [RFC RESEND] serial: 8250: fix regression in 8250 uart driver From: Andy Shevchenko To: dinh.linux@anniebear.net Cc: Dinh Nguyen , heikki.krogerus@linux.intel.com, peter@hurleysoftware.com, Greg Kroah-Hartman , linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org Date: Tue, 14 Jun 2016 19:00:46 +0300 In-Reply-To: References: <575F7325.3030907@kernel.org> <1465897220.30123.26.camel@linux.intel.com> Organization: Intel Finland Oy Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.20.3-1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2016-06-14 at 10:27 -0500, dinh.linux@anniebear.net wrote: > > > > On Mon, 2016-06-13 at 21:59 -0500, Dinh Nguyen wrote: > > > Apologies, but my original email bounced for Andy and Heikki, > > > resending. > > > ---- > > > > I suppose this one, i.e. commit dd4e91d538b3 ("dmaengine: slave > > means at > > least one of DMA_SLAVE, DMA_CYCLIC"), solves the issue. > > > > Hmm...that commit didn't seem to fix my issue. > > In regard to Peter's reply: > > "The error is that your dmaengine driver doesn't support the > functionality > required by the 8250 driver." Ah, sorry, indeed. Peter is right. > Does this mean that the 8250_dw.c driver can no longer use DMA? It means that previously the use of DMA engine whatever was used is not correct in your case. There is no issues in UART driver, the issue is in DMA controller driver. I'm working on a quirk that will allow user to enforce PIO mode for Rx/Tx or both. In that case if DMA controller can't be fixed you still might use DMA for Tx. -- Andy Shevchenko Intel Finland Oy