From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Frysinger Subject: Re: [Uclinux-dist-devel] [PATCH 1/5] netdev: bfin_mac: Blackfin EMAC interrupt may not be shared Date: Fri, 29 May 2009 18:21:41 -0400 Message-ID: <8bd0f97a0905291521m35731e0bra828cb09d0929974@mail.gmail.com> References: <8bd0f97a0905290445x3b0829f3h657fec534f290c7f@mail.gmail.com> <20090529.150928.239765896.davem@davemloft.net> <8bd0f97a0905291513m780898e9j6bd4c0b3b9ae8528@mail.gmail.com> <20090529.151816.232829085.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Michael.Hennerich@analog.com, netdev@vger.kernel.org, uclinux-dist-devel@blackfin.uclinux.org To: David Miller Return-path: Received: from yw-out-2324.google.com ([74.125.46.30]:59867 "EHLO yw-out-2324.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753824AbZE2WVk convert rfc822-to-8bit (ORCPT ); Fri, 29 May 2009 18:21:40 -0400 Received: by yw-out-2324.google.com with SMTP id 5so3611506ywb.1 for ; Fri, 29 May 2009 15:21:41 -0700 (PDT) In-Reply-To: <20090529.151816.232829085.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On Fri, May 29, 2009 at 18:18, David Miller wrote: > From: Mike Frysinger >> the difference is that one of these is required in order for anythin= g >> to get done and the other is always useless noise. =C2=A0also, the B= lackfin >> core does do speculative data fetching on external memory, but not >> MMRs, so the stalling due to the data cache line fills will be >> mitigated unlike the useless MMR reads. > > You only need to read the register if the descriptor status is not > ready yet, and you're just spinning in that case anyways. > > I doubt it makes any real difference if implemented properly. > > But I guess it's more fun to speculate than to actually try it out. > :-/ and i guess it's more fun to waste time attempting to support an operating mode that the hardware has never and most likely will never support -mike