From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfgang Grandegger Subject: Re: [PATCH 2/3] can: c_can: Provide generic interface to configure c-can message objects Date: Wed, 16 Jan 2013 10:03:31 +0100 Message-ID: <50F66CE3.8070302@grandegger.com> References: <50D31ADE.1050308@pengutronix.de> <50D37154.9020107@grandegger.com> <50F65A86.3060307@st.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from ngcobalt02.manitu.net ([217.11.48.102]:37765 "EHLO ngcobalt02.manitu.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932143Ab3APJDk (ORCPT ); Wed, 16 Jan 2013 04:03:40 -0500 In-Reply-To: <50F65A86.3060307@st.com> Sender: linux-can-owner@vger.kernel.org List-ID: To: Amit Virdi Cc: Marc Kleine-Budde , "linux-can@vger.kernel.org" , Bhupesh SHARMA , "anilkumar@ti.com" , spear-devel On 01/16/2013 08:45 AM, Amit Virdi wrote: > On 12/21/2012 1:43 AM, Wolfgang Grandegger wrote: >> On 12/20/2012 03:04 PM, Marc Kleine-Budde wrote: >>> On 12/20/2012 11:05 AM, Amit Virdi wrote: >>>> Depending on the underlying platform, the configuration of the c-can >>>> message objects can change. For e.g. in some systems, it makes more >>>> sense to receive many message objects and transmit very few. In any >>>> case, providing flexibility in configuring the message objects is >>>> highly >>>> desirable. >>>> >>>> The total number of message objects for C_CAN controller is fixed at >>>> 32. >>>> The receive message objects are assigned higher priority so they begin >>>> with message object#1. So, in order to configure the message object the >>>> driver just needs two parameters - rx_split (for differentiating >>>> between >>>> lower bucket and higher bucket) and tx_num. >>>> >>>> However, if the user doesn't specify these parameters, then the message >>>> objects are configured with default parameters with equal distribution >>>> of receive and transmit message objects (16 each). >>> >>> As Wolfgang pointed out, the DT should only describe the hardware. In >>> the ethernet world I think there is ethtool to configure the hardware. >>> Maybe we need something similar for CAN (or add CAN support to ethtool). >> >> Yeah, a simple tool using simple ioctl request would be nice, indeed. >> Well, as a per device setting seems overkill a simple module parameter >> would just do it. >> > > So, you're saying to drop the device configuration from the DT and use > some tool to do that. This would be nice if there are enough devices, > apart from the Bosch C-CAN controller, which require this sort of > configuration. No, I said: "a simple module parameter would just do it". Wolfgang.