From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752501AbaHOTOM (ORCPT ); Fri, 15 Aug 2014 15:14:12 -0400 Received: from www.linutronix.de ([62.245.132.108]:58108 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751628AbaHOTOK (ORCPT ); Fri, 15 Aug 2014 15:14:10 -0400 Message-ID: <53EE5BF8.3010007@linutronix.de> Date: Fri, 15 Aug 2014 21:14:00 +0200 From: Sebastian Andrzej Siewior User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.0 MIME-Version: 1.0 To: Lennart Sorensen CC: linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, tony@atomide.com, balbi@ti.com, Vinod Koul , Greg Kroah-Hartman Subject: Re: [PATCH v7] 8250-core based serial driver for OMAP + DMA References: <1408124563-31541-1-git-send-email-bigeasy@linutronix.de> <20140815181704.GH17769@csclub.uwaterloo.ca> In-Reply-To: <20140815181704.GH17769@csclub.uwaterloo.ca> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/15/2014 08:17 PM, Lennart Sorensen wrote: > Are you saying that with the new driver you have to respond to the RX > irq faster than before to avoid overflows? It is not quite clear. Yes. The irq fires 46 bytes giving you 16 bytes buffer before overflow vs 63 bytes buffer the old one had. > I do think 40000 interrupts to handle 40000 bytes of date does seem a > tad inefficient, so dropping to 854 looks a lot nicer. Was the omap > driver not using the fifo trigger levels at all? It configured the trigger levels to 1 for RX and 16 for TX. Sebastian