From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anton Vorontsov Subject: Re: Gianfar driver failing on MPC8641D based board Date: Tue, 2 Mar 2010 17:02:33 +0300 Message-ID: <20100302140233.GA14488@oksana.dev.rtsoft.ru> References: <20100226031452.GA11319@oksana.dev.rtsoft.ru> <4B87B937.6010204@ge.com> <20100226143532.GA31622@oksana.dev.rtsoft.ru> <4B87E01E.4070704@windriver.com> <4B87E662.3080106@ge.com> <4B87E9EF.3010604@ge.com> <20100226161058.GA22954@oksana.dev.rtsoft.ru> <4B87F67E.5070601@windriver.com> <20100226213825.GA32363@oksana.dev.rtsoft.ru> <9F4C7D19E8361D4C94921B95BE08B81BC93EC3@zin33exm22.fsl.freescale.net> Reply-To: avorontsov@ru.mvista.com Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Cc: Paul Gortmaker , Martyn Welch , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev list , davem@davemloft.net To: Kumar Gopalpet-B05799 Return-path: Content-Disposition: inline In-Reply-To: <9F4C7D19E8361D4C94921B95BE08B81BC93EC3@zin33exm22.fsl.freescale.net> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Hi! On Sat, Feb 27, 2010 at 11:05:32AM +0530, Kumar Gopalpet-B05799 wrote: [...] > Understood, and thanks for the explanation. Am I correct in saying that > this is > due to the out-of-order execution capability on powerpc ? Nope, that was just a logic issue in the driver. Though, with the patch, the eieio() is needed so that compiler (or CPU) won't reorder lstatus and skbuff writes. > I have one more question, why don't we use use atomic_t for num_txbdfree > and > completely do away with spin_locks in gfar_clean_tx_ring() and > gfar_start_xmit(). > In an non-SMP, scenario I would feel there is absolutely no requirement > of spin_locks > and in case of SMP atomic operation would be much more safer on powerpc > rather than spin_locks. > > What is your suggestion ? I think that's a good idea. However, in start_xmit() we'll have to keep the spinlock anyway since it also protects from gfar_error(), which can modify regs->tstat. Thanks! -- Anton Vorontsov email: cbouatmailru@gmail.com irc://irc.freenode.net/bd2