From mboxrd@z Thu Jan 1 00:00:00 1970 From: Grant Likely Subject: Re: [PATCH] spi: Driver for GPIO controlled SPI multiplexer Date: Mon, 04 Mar 2013 10:38:35 +0800 Message-ID: <20130304023835.5F0BC3E14C0@localhost> References: <1361973519-30633-1-git-send-email-peter.korsgaard@barco.com> <20130302173244.41A2B3E1089@localhost> <20130303074209.GA19020@opensource.wolfsonmicro.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, Dries Van Puymbroeck , Peter Korsgaard To: Mark Brown Return-path: In-Reply-To: <20130303074209.GA19020-yzvPICuk2AATkU/dhu1WVueM+bqZidxxQQ4Iyu8u01E@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: spi-devel-general-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: linux-spi.vger.kernel.org On Sun, 3 Mar 2013 15:42:39 +0800, Mark Brown wrote: > On Sat, Mar 02, 2013 at 05:32:44PM +0000, Grant Likely wrote: > > > Mark commented on this too, but I disagree with him on one point; it > > will actually be simpler if you finish up the transfer in the callback, > > and that it really should be implemented that way from day one. > > > xfer_complete and xfer_complete_wq can be dropped, and > > child_mesg_complete, child_mesg_context and child_mesg_dev will move > > into struct spi_mux_gpio. > > I agree with this, I was just thinking that the waitqueue looked like a > first stage in allowing multiple in flight transfers on the parent. > Unless I'm missing something, I didn't think too deeply about > implementing that, it's just that it's going to be needed at some point > as it's so important for performance. Alright, I'll bite. How? What's the scenario where the driver will need to manage the wait queue directly? The point of the transfer_one_message interface was pull queue management into the core and allow the driver to get the next message just when it needs it. g. ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_feb