From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933436Ab3AIVhF (ORCPT ); Wed, 9 Jan 2013 16:37:05 -0500 Received: from saturn.retrosnub.co.uk ([178.18.118.26]:39615 "EHLO saturn.retrosnub.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933281Ab3AIVhC (ORCPT ); Wed, 9 Jan 2013 16:37:02 -0500 Message-ID: <50EDE2FA.3060308@kernel.org> Date: Wed, 09 Jan 2013 21:36:58 +0000 From: Jonathan Cameron User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Lars-Peter Clausen CC: Grant Likely , Julia Lawall , spi-devel-general@lists.sourceforge.net, linux-kernel@vger.kernel.org, Jonathan Cameron , linux-iio@vger.kernel.org Subject: Re: [PATCH 1/3] spi: Add helper functions for setting up transfers References: <1357752671-30222-1-git-send-email-lars@metafoo.de> <50EDC309.5010104@kernel.org> <50EDD96A.5080900@metafoo.de> In-Reply-To: <50EDD96A.5080900@metafoo.de> X-Enigmail-Version: 1.4.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/09/2013 08:56 PM, Lars-Peter Clausen wrote: > On 01/09/2013 08:20 PM, Jonathan Cameron wrote: >> On 01/09/2013 05:31 PM, Lars-Peter Clausen wrote: >>> Quite often the pattern used for setting up and transferring a synchronous SPI >>> transaction looks very much like the following: >>> >>> struct spi_message msg; >>> struct spi_transfer xfers[] = { >>> ... >>> }; >>> >>> spi_message_init(&msg); >>> spi_message_add_tail(&xfers[0], &msg); >>> ... >>> spi_message_add_tail(&xfers[ARRAY_SIZE(xfers) - 1], &msg); >>> >>> ret = spi_sync(&msg); >>> >>> This patch adds two new helper functions for handling this case. The first >>> helper function spi_message_init_with_transfers() takes a spi_message and an >>> array of spi_transfers. It will initialize the message and then call >>> spi_message_add_tail() for each transfer in the array. E.g. the following >>> >>> spi_message_init(&msg); >>> spi_message_add_tail(&xfers[0], &msg); >>> ... >>> spi_message_add_tail(&xfers[ARRAY_SIZE(xfers) - 1], &msg); >>> >>> can be rewritten as >>> >>> spi_message_init_with_transfers(&msg, xfers, ARRAY_SIZE(xfers)); >>> >>> The second function spi_sync_transfer() takes a SPI device and an array of >>> spi_transfers. It will allocate a new spi_message (on the stack) and add all >>> transfers in the array to the message. Finally it will call spi_sync() on the >>> message. >>> >>> E.g. the follwing >>> >>> struct spi_message msg; >>> struct spi_transfer xfers[] = { >>> ... >>> }; >>> >>> spi_message_init(&msg); >>> spi_message_add_tail(&xfers[0], &msg); >>> ... >>> spi_message_add_tail(&xfers[ARRAY_SIZE(xfers) - 1], &msg); >>> >>> ret = spi_sync(spi, &msg); >>> >>> can be rewritten as >>> >>> struct spi_transfer xfers[] = { >>> ... >>> }; >>> >>> ret = spi_sync_transfer(spi, xfers, ARRAY_SIZE(xfers)); >>> >>> The patch also adds a new cocci script which can detect such sequences as >>> described above and transform them automatically to use the new helper >>> functions. >>> >>> Signed-off-by: Lars-Peter Clausen >>> >> Principle looks good to me and some nice little duplication removal >> savings. >> >> My coccinelle isn't really up to checking that, but for the functions >> Acked-by: Jonathan Cameron >> >> When all comments are in on the code we'll have to think about how to >> merge this. If you have much else planned that will hit those iio drivers >> then things will get uggly unless it goes through that tree. >> >> Guess it all depends on whether others like the patch though ;) > > The IIO patches can easily wait another release until the spi has made it's way > up into mainline. I just didn't want to send out the helper functions without > any realworld examples on how they can be used. > Good point, though obviously send them again after this patch has merged given the fine nature of my memory ;)