From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1948923AbcBSWWD (ORCPT ); Fri, 19 Feb 2016 17:22:03 -0500 Received: from devils.ext.ti.com ([198.47.26.153]:35131 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1946149AbcBSWWB (ORCPT ); Fri, 19 Feb 2016 17:22:01 -0500 Subject: Re: [PATCH v2 3/3] net: netcp: rework the code for get/set sw_data in dma desc To: Arnd Bergmann References: <1455904724-17952-1-git-send-email-m-karicheri2@ti.com> <1455904724-17952-4-git-send-email-m-karicheri2@ti.com> <3256728.DYdlef6xAF@wuerfel> CC: , , From: Murali Karicheri Organization: Texas Instruments Message-ID: <56C79585.1090905@ti.com> Date: Fri, 19 Feb 2016 17:21:57 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <3256728.DYdlef6xAF@wuerfel> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/19/2016 03:55 PM, Arnd Bergmann wrote: > On Friday 19 February 2016 12:58:44 Murali Karicheri wrote: >> SW data field in descriptor can be used by software to hold private >> data for the driver. As there are 4 words available for this purpose, >> use separate macros to place it or retrieve the same to/from >> descriptors. Also do type cast of data types accordingly. >> >> Cc: Wingman Kwok >> Cc: Mugunthan V N >> CC: Arnd Bergmann >> CC: Grygorii Strashko >> CC: David Laight >> Signed-off-by: Murali Karicheri > > Looks ok in principle. > > Acked-by: Arnd Bergmann > >> get_pkt_info(&dma_buf, &tmp, &dma_desc, ndesc); >> - get_sw_data((u32 *)&buf_ptr, &buf_len, ndesc); >> + /* warning!!!! We are retrieving the virtual ptr in the sw_data >> + * field as a 32bit value. Will not work on 64bit machines >> + */ >> + buf_ptr = (void *)GET_SW_DATA0(ndesc); >> + buf_len = (int)GET_SW_DATA1(desc); > > I would have abstracted the retrieval of a pointer again, > and added the comment in the helper function once, it doesn't > really need to be duplicated everywhere. > Arnd, I thought about it to add it to the API. API currently set buffer and ptr. It would be an issue only if store/retrieve ptr in/from the sw_data. So for the comment to be really useful to someone who is changing the code, doesn't it make sense to add it at the point of invocation as done in this patch? No? Murali > Arnd > -- Murali Karicheri Linux Kernel, Keystone