Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755424AbaKEQbK (ORCPT ); Wed, 5 Nov 2014 11:31:10 -0500 Received: from www.linutronix.de ([62.245.132.108]:37954 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755279AbaKEQbH (ORCPT ); Wed, 5 Nov 2014 11:31:07 -0500 Message-ID: <545A50BB.2020307@linutronix.de> Date: Wed, 05 Nov 2014 17:30:51 +0100 From: Sebastian Andrzej Siewior User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.2.0 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, gregkh@linuxfoundation.org, devicetree@vger.kernel.org Subject: Re: [PATCH 11/13] arm: dts: dra7: add DMA properties for UART References: <1412014009-13315-1-git-send-email-bigeasy@linutronix.de> <1412014009-13315-12-git-send-email-bigeasy@linutronix.de> <20141104170233.GB24112@csclub.uwaterloo.ca> <5459079D.7080703@linutronix.de> <20141104172117.GC24112@csclub.uwaterloo.ca> <20141104183315.GD24112@csclub.uwaterloo.ca> <20141104210315.GF24112@csclub.uwaterloo.ca> <20141105011506.GG24112@csclub.uwaterloo.ca> <5459DBB7.1090702@linutronix.de> <20141105153307.GN24110@csclub.uwaterloo.ca> <20141105162024.GH24112@csclub.uwaterloo.ca> In-Reply-To: <20141105162024.GH24112@csclub.uwaterloo.ca> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit 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 11/05/2014 05:20 PM, Lennart Sorensen wrote: > On Wed, Nov 05, 2014 at 10:33:15AM -0500, Lennart Sorensen wrote: >> Two systems ran 16 hours each so far with no issues. Pushed 170MB of >> data through the pair of serial ports on one system at 230400. > > The console on uart3 doesn't appear to be using the dma assuming the > values in /sys for the dma controller and bytes transferred mean anything. > It does mention in dmesg that it allocated dma channels for uart3 though. Then it should use it :) > How do you tell if it is using dma? There is omap_8250_tx_dma() and omap_8250_rx_dma(). Both setup callbacks (the rx+tx _complete). Upon successful DMA transfer you should see them invoked with bytes transfered (>0). For RX transfer you need at least trigger bytes in the FIFO within a given time frame (I think it was 46 bytes and the delay may be up to 2 bytes). If you miss this then DMA for RX won't wire and you purge the FIFO manually via "timeout-interrupt" (the callback will be invoked with an error condition and 0 bytes). Assuming this works for you then one should figure out why the counters in /sys are not updated? Sebastian -- 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/