From mboxrd@z Thu Jan 1 00:00:00 1970 From: Balaji Rao Subject: Re: [PATCH 0/2] spi: Add support for non-blocking synchronous transfers Date: Sun, 1 Mar 2009 15:53:35 +0530 Message-ID: <20090301102333.GD3103@fedora.yogi> References: <20090228081036.31964.80618.stgit@fedora.yogi> <200902281519.55341.david-b@pacbell.net> <20090301051103.GA3103@fedora.yogi> <200903010149.19845.david-b@pacbell.net> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: linux-kernel@vger.kernel.org, spi-devel-general@lists.sourceforge.net, Andy Green To: David Brownell Return-path: Content-Disposition: inline In-Reply-To: <200903010149.19845.david-b@pacbell.net> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-spi.vger.kernel.org On Sun, Mar 01, 2009 at 01:49:19AM -0800, David Brownell wrote: > On Saturday 28 February 2009, Balaji Rao wrote: > > > That leaves un-answered the question of what to do when > > > the SPI bus is busy performing some other transfer. =A0I > > > looked at your [2/2] patch, and saw it ignoring that very > > > basic issue ... this new call will just poke at the bus, > > > trashing any transfer that was ongoing. > >=20 > > We use s3c24xx_gpio as the master, which is a very simple gpio base= d > > bitbang.=20 > >=20 > > Yes, it is with this intention, interrupts are disabled around the > > actual bitbang code, so that it completes without being interrupted= =2E > > Doesn't this guarantee atomicity ? >=20 > Atomicity isn't the issue so much as the fact that if the > bus is in the middle of some transfer to one device, > your patch lets another device trash that transmission. >=20 > I don't know how many more times I can say that your > patches introduce DATA CORRUPTION to the system, but > it's surely not many more times. Yes, I get the point now. Sorry for not observing it earlier. - Balaji