Return-path: Received: from mail-qy0-f174.google.com ([209.85.216.174]:59670 "EHLO mail-qy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751075Ab1DFVB4 convert rfc822-to-8bit (ORCPT ); Wed, 6 Apr 2011 17:01:56 -0400 MIME-Version: 1.0 In-Reply-To: <1302123428.20093.6.camel@maggie> References: <1302033463-1846-1-git-send-email-zajec5@gmail.com> <1302123428.20093.6.camel@maggie> Date: Wed, 6 Apr 2011 23:01:55 +0200 Message-ID: Subject: Re: [RFC][PATCH] bcmai: introduce AI driver From: =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= To: =?UTF-8?Q?Michael_B=C3=BCsch?= Cc: Arend van Spriel , "linux-wireless@vger.kernel.org" , "John W. Linville" , Larry Finger , George Kashperko , "b43-dev@lists.infradead.org" , "linux-arm-kernel@lists.infradead.org" , Russell King , Arnd Bergmann , linuxdriverproject , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: W dniu 6 kwietnia 2011 22:57 użytkownik Michael Büsch napisał: > On Wed, 2011-04-06 at 22:42 +0200, Rafał Miłecki wrote: >> 2011/4/6 Rafał Miłecki : >> > If we want to have two drivers working on two (different) cores >> > simultaneously, we will have to add trivial mutex to group core >> > switching with core operation (read/write). >> >> With a little of work we could avoid switching and mutexes on no-host >> boards. MMIO is not limited to one core at once in such a case. > > I don't think that this is a problem at all. > All that magic does happen inside of the bus I/O handlers. > Just like SSB does it. > From a driver point of view, the I/O functions just need to > be atomic. > > For SSB it's not always 100% atomic, but we're always safe > due to some assumptions being made. But this is an SSB implementation > detail that is different from AXI. So don't look too closely > at the SSB implementation of the I/O functions. You certainly want > to implement them slightly differently in AXI. SSB currently doesn't > make use of the additional sliding windows, because they are not > available in the majority of SSB devices. > > The AXI bus subsystem will manage the sliding windows and the driver > doesn't know about the details. Sure, I've meant mutex inside bcmai (or whatever name), not on the driver side! In BCMAI: bcmai_read() { mutex_get(); switch_core(); ioread(); mutex_release(); } -- Rafał