Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759748Ab3CGUJX (ORCPT ); Thu, 7 Mar 2013 15:09:23 -0500 Received: from smarthost3.mail.uk.easynet.net ([212.135.6.13]:36667 "EHLO smarthost3.mail.uk.easynet.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758443Ab3CGUJU convert rfc822-to-8bit (ORCPT ); Thu, 7 Mar 2013 15:09:20 -0500 From: Jean-Francois Dagenais To: Olivier KSIKES CC: open list Subject: Re: w1_ds2408 linux driver Thread-Topic: w1_ds2408 linux driver Thread-Index: AQHODq+hzT4V6+pN0kSL+qstSY9rQJiaweUA Date: Thu, 7 Mar 2013 20:09:14 +0000 Message-ID: <47BBCF14-C7BC-4C35-826A-52A50EFB8B4B@sonatest.com> References: <51238FBA.9050600@okprods.com> In-Reply-To: <51238FBA.9050600@okprods.com> Accept-Language: en-CA, en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [192.168.128.91] x-exclaimer-md-config: 7c1584ba-e595-4fa0-82b4-f84c142522ec Content-Type: text/plain; charset="us-ascii" Content-ID: <1A56EFDEF2CED545B92C50063EA91341@Sonatest.com> Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-Mailshell-score: 2, threshold=98, smtpSenderIP=212.56.87.3 utc=<2013-03-07 20:09:18> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1535 Lines: 47 On 2013-02-19, at 9:44 AM, Olivier KSIKES wrote: > Dear Mr Dagenais, > > I have just tried your w1-ds2408 linux driver on a TP link mini router running openwrt with w1-gpio. I was able to successfully update a 2408 outputs by writing a byte to the /output file. > However, I would like to drive an LCD screen, and this method seems limited to 3/4 chars per second. > > I had little more luck driving the 2408 thru the generic w1 driver (using the rw file), where I reached around 25 bytes/s. > This is however far from the actual 1wire bus capabilities. > > Thus, I'm wondering if there is a faster way to output a series of bytes to the 2408 using your driver? > Is there any doc available apart from w1_ds2408.c comments? > > With best regards and congratulations for your great work, > > Olivier Ksikes Here are my test results. I have a simple main() that opens the /sys/bus/w1/devices/29-0000000xyz/output file and keeps it open. I sweep from 0 to 255 in a tight loop that simply does for (int i=0; i <= 1024; ++i) { file.putChar(i); file.seek(0); } return 0; I invoke this using "time" and do 1024/timespent to get: Current driver (w/read-back ): ~48 chars/seconds Improved driver (wo/read-back): ~98 chars/seconds patch will follow... Cheers. -- 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/