From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Donald" Subject: RE: Questions regarding adding a patch in linux/drivers/char/8250.c Date: Mon, 21 May 2012 20:54:58 +0800 Message-ID: <00b701cd3750$f09ced60$d1d6c820$@com.tw> References: <00a301cd3719$b3faa370$1befea50$@com.tw> <20120521103009.7f4be5e0@pyramind.ukuu.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from asix.com.tw ([113.196.140.82]:57679 "EHLO asix.com.tw" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755592Ab2EUM4C (ORCPT ); Mon, 21 May 2012 08:56:02 -0400 In-Reply-To: <20120521103009.7f4be5e0@pyramind.ukuu.org.uk> Content-Language: zh-tw Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: 'Alan Cox' Cc: linux-serial@vger.kernel.org Hi Alan, Thank you for your quick reply and nice questions. We will have an internal discussion regarding your questions and then I will reply to your questions as soon as possible. Regards, Donald -----Original Message----- From: Alan Cox [mailto:alan@lxorguk.ukuu.org.uk] Sent: Monday, May 21, 2012 5:30 PM To: Donald Cc: linux-serial@vger.kernel.org Subject: Re: Questions regarding adding a patch in linux/drivers/char/8250.c On Mon, 21 May 2012 14:19:34 +0800 "Donald" wrote: > Hi, > > This is Donald from ASIX Electronics Corp. My company has three PCI to Serial controllers, including MCS9845, MCS9835, and MCS9820. > Currently those serial devices using these three chips can directly > use the Linux kernel's serial driver in linux/drivers/char/8250.c. > Recently we find these three chips have a hardware bug relating to parity error count function. We have a software workaround for this issue. Below for reference is a pseudo code for this workaround. Actually I have a second question. Would it not be better to set the device to 8N1 and do the parity in software rather than lose the FIFO, especially at higher speeds ? Can you clarify what the erratum is triggered by ? Alan