Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754127Ab2HNOs0 (ORCPT ); Tue, 14 Aug 2012 10:48:26 -0400 Received: from lxorguk.ukuu.org.uk ([81.2.110.251]:45669 "EHLO lxorguk.ukuu.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751778Ab2HNOsW (ORCPT ); Tue, 14 Aug 2012 10:48:22 -0400 Date: Tue, 14 Aug 2012 15:52:27 +0100 From: Alan Cox To: Christophe Leroy Cc: Alan Cox , Vitaly Bordug , Marcelo Tosatti , linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH] Powerpc 8xx CPM_UART delay in receive Message-ID: <20120814155227.018988da@pyramind.ukuu.org.uk> In-Reply-To: <201208141426.q7EEQSPc003956@localhost.localdomain> References: <201208141426.q7EEQSPc003956@localhost.localdomain> X-Mailer: Claws Mail 3.8.0 (GTK+ 2.24.8; x86_64-redhat-linux-gnu) Face: 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 Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 857 Lines: 21 On Tue, 14 Aug 2012 16:26:28 +0200 Christophe Leroy wrote: > Hello, > > I'm not sure who to address this Patch to either > > It fixes a delay issue with CPM UART driver on Powerpc MPC8xx. > The problem is that with the actual code, the driver waits 32 IDLE patterns before returning the received data to the upper level. It means for instance about 1 second at 300 bauds. > This fix limits to one byte the waiting period. Take a look how the 8250 does it - I think you want to set the value based upon the data rate. Your patch will break it for everyone doing high seed I/O. Alan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/