From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laxman Dewangan Subject: Re: [PATCH] ARM: tegra: dts: add aliases and DMA requestor for serial controller Date: Thu, 20 Dec 2012 11:45:30 +0530 Message-ID: <50D2AD02.6060101@nvidia.com> References: <1355898671-3960-1-git-send-email-ldewangan@nvidia.com> <50D1F2CB.3090206@wwwdotorg.org> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <50D1F2CB.3090206-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Stephen Warren Cc: "linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org" , "linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: linux-tegra@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");