Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756020AbXLTAWt (ORCPT ); Wed, 19 Dec 2007 19:22:49 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752885AbXLTAWm (ORCPT ); Wed, 19 Dec 2007 19:22:42 -0500 Received: from proxy3.bredband.net ([195.54.101.73]:47566 "EHLO proxy3.bredband.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751243AbXLTAWl convert rfc822-to-8bit (ORCPT ); Wed, 19 Dec 2007 19:22:41 -0500 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AuE6ALVEaUdV4n6YRmdsb2JhbACHYYgWAQEBN5oKAw Message-ID: <024201c8429e$6df3f670$3ba6fea9@atmel.com> From: "Ulf Samuelsson" To: "Haavard Skinnemoen" , "Andrew Victor" Cc: "Russell King" , "Haavard Skinnemoen" , , , "Remy Bohmer" , References: <1198077130-9021-1-git-send-email-hskinnemoen@atmel.com> Subject: Re: [PATCH v2 0/6] atmel_serial: Cleanups, irq handler splitup & DMA Date: Wed, 19 Dec 2007 23:13:53 +0100 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3198 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1503 Lines: 36 | The following patchset cleans up the atmel_serial driver a bit, | moves a significant portion of the interrupt handler into a tasklet, | and adds DMA support. This is the result of a combined effort by Chip | Coldwell, Remy Bohmer and me. The patches should apply cleanly onto | Linus' latest git tree. | | With DMA, I see transfer rates around 92 kbps when transferring a big | file using ZModem (both directions are roughly the same.) | The start and stop bits will use 20 % of the bit rate so the teoretical max throughput at 115,200 BAUD is 115,200 * 0,8 = 92160 bps. What would be interesting is to figure out if we can get reliable transmission at higher frequencies - 230/460/921 kbps. | Note that break and error handling doesn't work too well with DMA | enabled. This is a common problem with all the efforts I've seen | adding DMA support to this driver (including my own). The PDC error | handling also accesses icount without locking. I'm tempted to just | ignore the problem for now and hopefully come up with a solution | later. Have told the guys responsible for the USART IP block we need to improve the H/W for error control for the last 3-4 years. Why not at 120000 gates/sq mm, add error counters??? Best Regards Ulf Samuelsson -- 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/