From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Herrenschmidt Subject: Re: [PATCH] PPC4xx UART0 (8250) problem Date: Sat, 07 Apr 2007 15:12:36 +1000 Message-ID: <1175922756.7407.46.camel@localhost.localdomain> References: <46171C50.3020104@faust.net.ua> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from gate.crashing.org ([63.228.1.57]:55976 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752069AbXDGFMo (ORCPT ); Sat, 7 Apr 2007 01:12:44 -0400 In-Reply-To: <46171C50.3020104@faust.net.ua> Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: Mikhail Zolotaryov Cc: mporter@kernel.crashing.org, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org On Sat, 2007-04-07 at 07:21 +0300, Mikhail Zolotaryov wrote: > On PPC4xx embedded we often have UART0 on IRQ0 but 8250 UART driver > uses IRQ0 as "no irq" hack. It's suggested that platforms with UART > on IRQ0 will redefine is_real_interrupt(irq) macro but 8250 code > anyway overrides that. As the result, serial line on UART0 works > on polling-way and we have character loss on high baud rates. > > In patch I added check if UART0 is on IRQ0, if so we define > is_real_interrupt macro to be 1 (true). Also, check if > is_real_interrupt macro is already defined added to 8250 UART > driver. This is an old problem. The proper fix is already implemented for arch/powerpc and consist of having virtual irq numbers (which helps for many other things anyway). Support for 4xx platforms in arch/powerpc is starting to get in, pop on linuxppc-dev@ozlabs.org where the patches are being posted and you are welcome to give a hand porting more platforms over :-) Ben.