From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751855Ab0CUHbn (ORCPT ); Sun, 21 Mar 2010 03:31:43 -0400 Received: from fg-out-1718.google.com ([72.14.220.159]:50181 "EHLO fg-out-1718.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751201Ab0CUHbl (ORCPT ); Sun, 21 Mar 2010 03:31:41 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; b=OEx2nNusyOQipcvEUBTdA35EZQn2BFFQSh7I4G0xd5bfs9QW2Sm4lUbR2plKm6gcbN D4/OvBqsDiO8LAGX4F4amEHLmkDQsJC7BbSIruy8JISzQ8LP3K/X9BYu/eMCp9RWk8hH lSEGkGYk8NEMHJrly2qEVnUfNQohrNI7BWR4I= MIME-Version: 1.0 In-Reply-To: References: <1268987934-22690-1-git-send-email-chripell@fsfe.org> Date: Sun, 21 Mar 2010 08:31:39 +0100 X-Google-Sender-Auth: 7e360e3c35eb5068 Message-ID: Subject: Re: [PATCH 1/3] max3100: added raise_threaded_irq From: christian pellegrin To: Grant Likely Cc: feng.tang@intel.com, akpm@linux-foundation.org, greg@kroah.com, david-b@pacbell.net, alan@lxorguk.ukuu.org.uk, spi-devel-general@lists.sourceforge.net, linux-serial@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Linux Kernel Mailing List Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Fri, Mar 19, 2010 at 6:48 PM, Grant Likely wrote: > You should cc: Thomas and Ingo and lkml (which I just did) on patches > to the threaded interrupt code. > ok, let me explain the reason for this function. The move from worqueues to the threaded interrupts was motivated by a reduction of latency in answering to RX buffer full interrupts. Threaded interrupts are SCHED_FIFO instead worqueues being SCHED_OTHER. In the case of MAX31x0 when we transmit a character we could have to receive one (this is efficient because SPI transfers are quite always bidirectional). The same routine is used both for tx and rx (an other things like changing parameters): this makes locking really simple. With this routine the thread interrupt handler could be the only kind of deferred work a driver for a simple hardware may ever need. -- Christian Pellegrin, see http://www.evolware.org/chri/ "Real Programmers don't play tennis, or any other sport which requires you to change clothes. Mountain climbing is OK, and Real Programmers wear their climbing boots to work in case a mountain should suddenly spring up in the middle of the computer room."