From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752512Ab2LTGPj (ORCPT ); Thu, 20 Dec 2012 01:15:39 -0500 Received: from hqemgate03.nvidia.com ([216.228.121.140]:17803 "EHLO hqemgate03.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750991Ab2LTGPc (ORCPT ); Thu, 20 Dec 2012 01:15:32 -0500 X-PGP-Universal: processed; by hqnvupgp08.nvidia.com on Wed, 19 Dec 2012 22:15:30 -0800 Message-ID: <50D2AD02.6060101@nvidia.com> Date: Thu, 20 Dec 2012 11:45:30 +0530 From: Laxman Dewangan User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.13) Gecko/20101208 Thunderbird/3.1.7 MIME-Version: 1.0 To: Stephen Warren CC: "linux@arm.linux.org.uk" , "linux-tegra@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] ARM: tegra: dts: add aliases and DMA requestor for serial controller References: <1355898671-3960-1-git-send-email-ldewangan@nvidia.com> <50D1F2CB.3090206@wwwdotorg.org> In-Reply-To: <50D1F2CB.3090206@wwwdotorg.org> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 19 December 2012 10:30 PM, Stephen Warren wrote: > On 12/18/2012 11:31 PM, Laxman Dewangan wrote: >> Add APB DMA requestor and serial aliases for serial controller. >> There will be two serial driver i.e. 8250 based simple serial driver >> and APB DMA based serial driver for higher baudrate and performace. >> >> The simple serial driver get enabled with compatible nvidia,tegra20-uart >> and APB DMA based driver will get enabled with compatible >> nvidia,tegra20-hsuart. > This patch seems to do two things: > > 1) Add a comment describing how to select the basic or DMA-based driver. > I can see why this is useful. > > 2) Add aliases for the serial ports. I have no idea why this is useful. Serial aliases are added because we want to get the port number like /dev/ttyTHS0, /d/ttyTHS2 etc. The uarta should be /dev/ttyTHS0 and uartc should be /dev/ttyTHS2. The port number can be found using aliases and of_alias_get_id() in driver file: port_number = of_alias_get_id(np, "serial");